diff --git a/.travis.yml b/.travis.yml
index 0393405..c524add 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -12,11 +12,12 @@ python:
 # command to install dependencies
 install:
   - "pip install --upgrade pip"
-  - "pip install flake8 python-coveralls '.[tests]'"
+  - "pip install flake8 python-coveralls sphinx '.[tests]'"
 # command to run tests
 script:
   - "flake8 --ignore=E501 ."
   - "pytest --cov=itunesiap -vv tests/"
+  - "python -msphinx -M html docs build"
 after_success:
   - "coveralls"
   - bash <(curl -s https://codecov.io/bash) || echo "Codecov did not collect coverage reports"
diff --git a/README.rst b/README.rst
index 56506eb..6dc2dec 100644
--- a/README.rst
+++ b/README.rst
@@ -6,18 +6,10 @@ itunes-iap v2
 .. image:: https://coveralls.io/repos/github/youknowone/itunes-iap/badge.svg?branch=master
     :target: https://coveralls.io/github/youknowone/itunes-iap?branch=master
 
-Note for v1 users
+The quick example
 -----------------
 
-There was breaking changes between v1 and v2 APIs.
-
-- Specify version `0.6.6` for latest v1 API when you don't need new APIs.
-- Or use `import itunesiap.legacy as itunesiap` instead of `import itunesiap`. (`from itunesiap import xxx` to `from itunesiap.legacy import xxx`)
-
-Quick example
--------------
-
-Create request to create a request to itunes verify api.
+Create request to create a request to itunes verifying api.
 
 .. sourcecode:: python
 
@@ -28,53 +20,53 @@ Create request to create a request to itunes verify api.
    >>>     print('invalid receipt')
    >>> print response.receipt.last_in_app.product_id  # other values are also available as property!
 
-Practical values are: product_id, original_transaction_id, quantity, unique_identifier
+Practically useful attributes are:
+    `product_id`, `original_transaction_id`, `quantity` and `unique_identifier`.
 
-Quick example with password (Apple Shared Secret)
--------------------------------------------------
+See the full document in:
+    - :func:`itunesiap.verify`: The verifying function.
+    - :class:`itunesiap.receipt.InApp`: The receipt object.
 
-Create request to create a request to itunes verify api.
 
-.. sourcecode:: python
+Installation
+------------
 
-   >>> import itunesiap
-   >>> try:
-   >>>     response = itunesiap.verify(raw_data, password)  # Just add password
-   >>> except itunesiap.exc.InvalidReceipt as e:
-   >>>     print('invalid receipt')
-   >>> in_app = response.receipt.last_in_app  # Get the latest receipt returned by Apple
+PyPI is the recommended way.
 
+.. sourcecode:: shell
 
-Verification policy
--------------------
+    $ pip install itunesiap
 
-Set verification mode for production or sandbox api. Review mode also available for appstore review.
+To browse versions and tarballs, visit:
+    `<https://pypi.python.org/pypi/itunes-iap/>`_
 
-.. sourcecode:: python
 
-   >>> import itunesiap
-   >>> # `review` enables both production and sandbox for appstore review. `production`, `sandbox` or `review` is available.
-   >>> response = request.verify(raw_data, env=itunesiap.env.review)
+Apple in-review mode
+--------------------
+
+In review mode, your actual users who use older versions want to verify in
+production server but the reviewers in Apple office want to verify in sandbox
+server.
 
-Or
+Note: The default env is `production` mode which doesn't allow any sandbox
+verifications.
+
+You can change the verifying mode by specifying `env`.
 
 .. sourcecode:: python
 
-   >>> import itunesiap
-   >>> response = itunesiap.verify(raw_data, use_sandbox=True):  # additional change for current environment.
+    >>> # review mode
+    >>> itunesiap.verify(raw_data, env=itunesiap.env.review)
 
-Proxy
------
 
-Put `proxy_url` for proxies.
+Note for v1 users
+-----------------
 
-.. sourcecode:: python
+There was breaking changes between v1 and v2 APIs.
+
+- Specify version `0.6.6` for latest v1 API when you don't need new APIs.
+- Or use `import itunesiap.legacy as itunesiap` instead of `import itunesiap`. (`from itunesiap import xxx` to `from itunesiap.legacy import xxx`)
 
-   >>> import itunesiap
-   >>> try:
-   >>>     response = itunesiap.verify(raw_data, proxy_url='https://your.proxy.url/')
-   >>> except itunesiap.exc.InvalidReceipt as e:
-   >>>     ...
 
 Contributors
 ------------
diff --git a/docs/conf.py b/docs/conf.py
new file mode 100644
index 0000000..0b15ec8
--- /dev/null
+++ b/docs/conf.py
@@ -0,0 +1,183 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+
+def get_version():
+    with open('../itunesiap/version.txt') as f:
+        return f.read().strip()
+
+#
+# itunes-iap documentation build configuration file, created by
+# sphinx-quickstart on Sat Jul 22 17:34:06 2017.
+#
+# This file is execfile()d with the current directory set to its
+# containing dir.
+#
+# Note that not all possible configuration values are present in this
+# autogenerated file.
+#
+# All configuration values have a default; values that are commented out
+# serve to show the default.
+
+# If extensions (or modules to document with autodoc) are in another directory,
+# add these directories to sys.path here. If the directory is relative to the
+# documentation root, use os.path.abspath to make it absolute, like shown here.
+#
+# import os
+# import sys
+# sys.path.insert(0, os.path.abspath('.'))
+
+
+# -- General configuration ------------------------------------------------
+
+# If your documentation needs a minimal Sphinx version, state it here.
+#
+# needs_sphinx = '1.0'
+
+# Add any Sphinx extension module names here, as strings. They can be
+# extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
+# ones.
+extensions = [
+    'sphinx.ext.autodoc',
+    'sphinx.ext.doctest',
+    'sphinx.ext.intersphinx',
+    'sphinx.ext.coverage']
+
+# Add any paths that contain templates here, relative to this directory.
+templates_path = ['_templates']
+
+# The suffix(es) of source filenames.
+# You can specify multiple suffix as a list of string:
+#
+# source_suffix = ['.rst', '.md']
+source_suffix = '.rst'
+
+# The master toctree document.
+master_doc = 'index'
+
+# General information about the project.
+project = 'itunes-iap'
+copyright = '2017, Jeong YunWon'
+author = 'Jeong YunWon'
+
+# The version info for the project you're documenting, acts as replacement for
+# |version| and |release|, also used in various other places throughout the
+# built documents.
+#
+# The short X.Y version.
+version = get_version()
+# The full version, including alpha/beta/rc tags.
+release = get_version()
+
+# The language for content autogenerated by Sphinx. Refer to documentation
+# for a list of supported languages.
+#
+# This is also used if you do content translation via gettext catalogs.
+# Usually you set "language" from the command line for these cases.
+language = None
+
+# List of patterns, relative to source directory, that match files and
+# directories to ignore when looking for source files.
+# This patterns also effect to html_static_path and html_extra_path
+exclude_patterns = []
+
+# The name of the Pygments (syntax highlighting) style to use.
+pygments_style = 'sphinx'
+
+# If true, `todo` and `todoList` produce output, else they produce nothing.
+todo_include_todos = False
+
+
+# -- Options for HTML output ----------------------------------------------
+
+# The theme to use for HTML and HTML Help pages.  See the documentation for
+# a list of builtin themes.
+#
+html_theme = 'alabaster'
+
+# Theme options are theme-specific and customize the look and feel of a theme
+# further.  For a list of options available for each theme, see the
+# documentation.
+#
+# html_theme_options = {}
+
+# Add any paths that contain custom static files (such as style sheets) here,
+# relative to this directory. They are copied after the builtin static files,
+# so a file named "default.css" will overwrite the builtin "default.css".
+html_static_path = ['_static']
+
+# Custom sidebar templates, must be a dictionary that maps document names
+# to template names.
+#
+# This is required for the alabaster theme
+# refs: http://alabaster.readthedocs.io/en/latest/installation.html#sidebars
+html_sidebars = {
+    '**': [
+        'about.html',
+        'navigation.html',
+        'relations.html',  # needs 'show_related': True theme option to display
+        'searchbox.html',
+        'donate.html',
+    ]
+}
+
+
+# -- Options for HTMLHelp output ------------------------------------------
+
+# Output file base name for HTML help builder.
+htmlhelp_basename = 'itunesiapdoc'
+
+
+# -- Options for LaTeX output ---------------------------------------------
+
+latex_elements = {
+    # The paper size ('letterpaper' or 'a4paper').
+    #
+    # 'papersize': 'letterpaper',
+
+    # The font size ('10pt', '11pt' or '12pt').
+    #
+    # 'pointsize': '10pt',
+
+    # Additional stuff for the LaTeX preamble.
+    #
+    # 'preamble': '',
+
+    # Latex figure (float) alignment
+    #
+    # 'figure_align': 'htbp',
+}
+
+# Grouping the document tree into LaTeX files. List of tuples
+# (source start file, target name, title,
+#  author, documentclass [howto, manual, or own class]).
+latex_documents = [
+    (master_doc, 'itunes-iap.tex', 'itunes-iap Documentation',
+     'Jeong YunWon', 'manual'),
+]
+
+
+# -- Options for manual page output ---------------------------------------
+
+# One entry per manual page. List of tuples
+# (source start file, name, description, authors, manual section).
+man_pages = [
+    (master_doc, 'itunes-iap', 'itunes-iap Documentation',
+     [author], 1)
+]
+
+
+# -- Options for Texinfo output -------------------------------------------
+
+# Grouping the document tree into Texinfo files. List of tuples
+# (source start file, target name, title, author,
+#  dir menu entry, description, category)
+texinfo_documents = [
+    (master_doc, 'itunes-iap', 'itunes-iap Documentation',
+     author, 'itunes-iap', 'One line description of project.',
+     'Miscellaneous'),
+]
+
+
+# Example configuration for intersphinx: refer to the Python standard library.
+intersphinx_mapping = {'https://docs.python.org/': None}
diff --git a/docs/environment.rst b/docs/environment.rst
new file mode 100644
index 0000000..7119aea
--- /dev/null
+++ b/docs/environment.rst
@@ -0,0 +1,14 @@
+Environment
+===========
+
+.. automodule:: itunesiap.environment
+
+
+.. autoclass:: itunesiap.environment.Environment
+    :members:
+
+.. autodata:: itunesiap.environment.default
+.. autodata:: itunesiap.environment.production
+.. autodata:: itunesiap.environment.sandbox
+.. autodata:: itunesiap.environment.review
+.. autodata:: itunesiap.environment.unsafe
diff --git a/docs/index.rst b/docs/index.rst
new file mode 100644
index 0000000..4613009
--- /dev/null
+++ b/docs/index.rst
@@ -0,0 +1,25 @@
+.. itunes-iap documentation master file, created by
+   sphinx-quickstart on Sat Jul 22 17:34:06 2017.
+   You can adapt this file completely to your liking, but it should at least
+   contain the root `toctree` directive.
+
+iTunes In-App purchase verification in Python
+=============================================
+
+.. toctree::
+   :maxdepth: 2
+   :caption: Contents:
+
+   quick.rst
+   request.rst
+   receipt.rst
+   environment.rst
+
+.. include:: ../README.rst
+
+Indices and tables
+==================
+
+* :ref:`genindex`
+* :ref:`modindex`
+* :ref:`search`
diff --git a/docs/quick.rst b/docs/quick.rst
new file mode 100644
index 0000000..45c3171
--- /dev/null
+++ b/docs/quick.rst
@@ -0,0 +1,71 @@
+The quick guide
+===============
+
+Create request to create a request to itunes verify api.
+
+.. sourcecode:: python
+
+    >>> import itunesiap
+    >>> try:
+    >>>     response = itunesiap.verify(raw_data)  # base64-encoded data
+    >>> except itunesiap.exc.InvalidReceipt as e:
+    >>>     print('invalid receipt')
+    >>> print response.receipt.last_in_app.product_id
+    >>> # other values are also available as properties!
+
+Practically useful attributes are: `product_id`, `original_transaction_id`, `quantity` and `unique_identifier`.
+See the full document in :class:`itunesiap.receipt.InApp`.
+
+itunesiap.verify()
+------------------
+Note that most of the use cases are covered by the :func:`itunesiap.verify`
+function.
+
+.. autofunction:: itunesiap.verify
+
+Apple in-review mode
+--------------------
+
+In review mode, your actual users who use older versions want to verify in
+production server but the reviewers in Apple office want to verify in sandbox
+server.
+
+Note: The default env is `production` mode which doesn't allow any sandbox
+verifications.
+
+You can change the verifying mode by specifying `env`.
+
+.. sourcecode:: python
+
+    >>> # review mode
+    >>> itunesiap.verify(raw_data, env=itunesiap.env.review)
+    >>> # sandbox mode
+    >>> itunesiap.verify(raw_data, env=itunesiap.env.sandbox)
+
+Also directly passing arguments are accepted:
+
+.. sourcecode:: python
+
+    >>> # review mode
+    >>> itunesiap.verify(raw_data, use_production=True, use_sandbox=True)
+
+
+Password for shared secret
+--------------------------
+
+When you have shared secret for your app, the verifying process requires a
+shared secret password.
+
+About the shared secret, See: In-App_Purchase_Configuration_Guide_.
+
+.. sourcecode:: python
+
+    >>> try:
+    >>>     # Add password as a parameter
+    >>>     response = itunesiap.verify(raw_data, password=password)
+    >>> except itunesiap.exc.InvalidReceipt as e:
+    >>>     print('invalid receipt')
+    >>> in_app = response.receipt.last_in_app  # Get the latest receipt returned by Apple
+
+
+.. _In-App_Purchase_Configuration_Guide: https://developer.apple.com/library/content/documentation/LanguagesUtilities/Conceptual/iTunesConnectInAppPurchase_Guide/Chapters/CreatingInAppPurchaseProducts.html
\ No newline at end of file
diff --git a/docs/receipt.rst b/docs/receipt.rst
new file mode 100644
index 0000000..d31fd08
--- /dev/null
+++ b/docs/receipt.rst
@@ -0,0 +1,23 @@
+Receipt
+=======
+
+.. automodule:: itunesiap.receipt
+
+.. autoclass:: itunesiap.receipt.ObjectMapper
+    :members:
+
+.. autoclass:: itunesiap.receipt.Response
+    :members: __EXPORT_FILTERS__, __WHITELIST__
+    :special-members:
+    :undoc-members:
+
+.. autoclass:: itunesiap.receipt.Receipt
+    :members: __EXPORT_FILTERS__, __WHITELIST__
+    :special-members:
+    :undoc-members:
+
+.. autoclass:: itunesiap.receipt.InApp
+    :members: __EXPORT_FILTERS__, __WHITELIST__
+    :special-members:
+    :undoc-members:
+
diff --git a/docs/request.rst b/docs/request.rst
new file mode 100644
index 0000000..b0257f0
--- /dev/null
+++ b/docs/request.rst
@@ -0,0 +1,13 @@
+Request
+=======
+
+.. automodule:: itunesiap.request
+
+.. autoclass:: itunesiap.request.Request
+    :members:
+
+.. automodule:: itunesiap.exceptions
+
+.. autoexception:: itunesiap.exceptions.ItunesServerNotAvailable
+.. autoexception:: itunesiap.exceptions.ItunesServerNotReachable
+.. autoexception:: itunesiap.exceptions.InvalidReceipt
diff --git a/itunesiap/environment.py b/itunesiap/environment.py
index 81d31a1..1a95707 100644
--- a/itunesiap/environment.py
+++ b/itunesiap/environment.py
@@ -1,4 +1,48 @@
+""":mod:`itunesiap.environment`
 
+:class:`Environment` is designed to pass pre-defined policies in easy way.
+The major use cases are provided as pre-defined constants.
+
+How to use environments
+-----------------------
+
+The default policy is `default` and it is the same to `production`. When your
+development lifecycle is proceed, you want to change it to `sandbox` or
+`review`.
+
+The recommended way to use environments is passing the value to
+:func:`itunesiap.verify` function as keyword argument `env`.
+
+.. sourcecode:: python
+
+    >>> itunesiap.verify(receipt, env=itunesiap.env.production)
+    >>> itunesiap.verify(receipt, env=itunesiap.env.sandbox)
+    >>> itunesiap.verify(receipt, env=itunesiap.env.review)
+
+
+Review mode
+-----------
+
+This is useful when your server is being used both for real users and Apple
+reviewers.
+Using review mode for a real service is possible, but be aware of: it is not
+100% safe. Your testers can getting advantage of free IAP in production
+version.
+A rough solution what I suggest is:
+
+.. sourcecode:: python
+
+    >>> if client_version == review_version:
+    >>>     env = itunesiap.env.review
+    >>> else:
+    >>>     env = itunesiap.env.production
+    >>>
+    >>> itunesiap.verify(receipt, env=env)
+
+
+Environment
+-----------
+"""
 from itunesiap.tools import deprecated
 
 __all__ = ('Environment', 'default', 'production', 'sandbox', 'review')
@@ -11,18 +55,29 @@ def push(self, env):
 
 
 class Environment(object):
-    """Environment provides option preset for `Request`. `default` is default"""
+    """Environment provides option preset for `Request`. `default` is default.
+
+    By passing an environment object to :func:`itunesiap.verify` or
+    :func:`itunesiap.request.Request.verify` function, it replaces verifying
+    policies.
+    """
 
-    ITEMS = ('use_production', 'use_sandbox')
+    ITEMS = (
+        'use_production', 'use_sandbox', 'timeout', 'exclude_old_transactions',
+        'verify_ssl')
 
     def __init__(self, **kwargs):
         self.use_production = kwargs.get('use_production', True)
         self.use_sandbox = kwargs.get('use_sandbox', False)
         self.timeout = kwargs.get('timeout', None)
-        self.verify_ssl = kwargs.get('verify_ssl', True)
         self.exclude_old_transactions = kwargs.get('exclude_old_transactions', False)
+        self.verify_ssl = kwargs.get('verify_ssl', True)
+
+    def __repr__(self):
+        return u'<{self.__class__.__name__} use_production={self.use_production} use_sandbox={self.use_sandbox} timeout={self.timeout} exclude_old_transactions={self.exclude_old_transactions} verify_ssl={self.verify_ssl}>'.format(self=self)
 
     def clone(self, **kwargs):
+        """Clone the environment with additional parameter override"""
         options = self.extract()
         options.update(**kwargs)
         return self.__class__(**options)
@@ -65,15 +120,20 @@ def current(cls):
         return cls._stack[-1]
 
 
+#: Use only production server with 30 seconds of timeout.
 default = Environment(use_production=True, use_sandbox=False, timeout=30.0, verify_ssl=True)
+#: Use only production server with 30 seconds of timeout.
 production = Environment(use_production=True, use_sandbox=False, timeout=30.0, verify_ssl=True)
+#: Use only sandbox server with 30 seconds of timeout.
 sandbox = Environment(use_production=False, use_sandbox=True, timeout=30.0, verify_ssl=True)
+
 review = Environment(use_production=True, use_sandbox=True, timeout=30.0, verify_ssl=True)
+#: Use both production and sandbox servers with 30 seconds of timeout.
 
 unsafe = Environment(use_production=True, use_sandbox=True, verify_ssl=False)
 
 
-Environment._stack.push(default)  # for backward compatibility
+Environment._stack.append(default)  # for backward compatibility
 
 
 @deprecated
diff --git a/itunesiap/exceptions.py b/itunesiap/exceptions.py
index bf74a89..22d5fc1 100644
--- a/itunesiap/exceptions.py
+++ b/itunesiap/exceptions.py
@@ -1,4 +1,4 @@
-
+""":mod:`itunesiap.exceptions`"""
 from prettyexc import PrettyException as E
 
 
@@ -7,14 +7,15 @@ class RequestError(E):
 
 
 class ItunesServerNotAvailable(RequestError):
-    pass
+    '''iTunes server is not available. No response.'''
 
 
 class ItunesServerNotReachable(ItunesServerNotAvailable):
-    pass
+    '''iTunes server is not reachable - including connection timeout.'''
 
 
 class InvalidReceipt(RequestError):
+    '''A receipt was given by iTunes server but it has error.'''
     _req_kwargs_keys = ['status']
     _descriptions = {
         21000: 'The App Store could not read the JSON object you provided.',
diff --git a/itunesiap/receipt.py b/itunesiap/receipt.py
index 140c69d..49c35f3 100644
--- a/itunesiap/receipt.py
+++ b/itunesiap/receipt.py
@@ -1,4 +1,8 @@
+""":mod:`itunesiap.receipt`
 
+A successful response returns a JSON object including receipts. To manipulate
+them in convinient way, `itunes-iap` wrapped it with :class:`ObjectMapper`.
+"""
 import pytz
 import dateutil.parser
 import warnings
@@ -40,7 +44,29 @@ def _to_bool(data):
 
 
 class ObjectMapper(object):
-    """Pretty interface for decoded receipt object.
+    """A pretty interface for decoded receipt object.
+
+    `__WHITELIST__` is a managed list of names. They are regarded as safe
+    values and guaranteed to be converted in python representation when needed.
+    `__EXPORT_FILTERS__` decides how to convert raw data to python
+    representation.
+
+    To access to the converted value, use a dictionary key as an attribute name.
+    For example, the key `receipt` is accessible by:
+
+    .. sourcecode:: python
+
+        >>> mapper.receipt  # return converted python object Receipt
+        >>> # == Receipt(mapper._['receipt'])
+
+    To access to the raw JSON value, use a dictionary key as an attribute name
+    but with the prefix `_`. For example, the key `receipt` is accessible by:
+
+        >>> mapper._receipt  # return converted python object Receipt
+        >>> # == mapper._['receipt']
+
+    :param dict data: A JSON object.
+    :return: :class:`ObjectMapper`
     """
     __WHITELIST__ = []
     __EXPORT_FILTERS__ = {}
@@ -78,7 +104,8 @@ def __getattr__(self, item):
 class Response(ObjectMapper):
     """The root response.
 
-    status: See https://developer.apple.com/library/ios/releasenotes/General/ValidateAppStoreReceipt/Chapters/ValidateRemotely.html#//apple_ref/doc/uid/TP40010573-CH104-SW1
+    About the value of status:
+        - See https://developer.apple.com/library/ios/releasenotes/General/ValidateAppStoreReceipt/Chapters/ValidateRemotely.html#//apple_ref/doc/uid/TP40010573-CH104-SW1
     """
     __WHITELIST__ = ['receipt', 'latest_receipt']  # latest_receipt_info
     __EXPORT_FILTERS__ = {'status': int}
@@ -93,11 +120,22 @@ def latest_receipt(self):
 
 
 class Receipt(ObjectMapper):
+    """The actual receipt.
+
+    The receipt may hold only one purchase directly in receipt object or may
+    hold multiple purchases in `in_app` key.
+    This object encapsulate it to list of :class:`InApp` object in `in_app`
+    property.
+    """
     __WHITELIST__ = ['in_app']
     __EXPORT_FILTERS__ = {}
 
     @lazy_property
     def in_app(self):
+        """The list of purchases. If the receipt has receipt keys in the
+        receipt body, it still will be wrapped as an :class:`InApp` and consists
+        of this property
+        """
         if 'in_app' in self._:
             return list(map(InApp, self._in_app))
         else:
@@ -105,11 +143,26 @@ def in_app(self):
 
     @property
     def last_in_app(self):
+        """The last item in `in_app` property order by purchase_date."""
         return sorted(
             self.in_app, key=lambda x: x['original_purchase_date_ms'])[-1]
 
 
 class InApp(ObjectMapper):
+    """The individual purchases.
+
+    The major keys are `unique_identifier`, `quantity`, `product_id` and
+    `transaction_id`. `quantty` and `product_id` mean what kind of product and
+    and how many of them the customer bought. `unique_identifier` and
+    `transaction_id` is used to check where it is processed and track related
+    purchases.
+
+    For the detail, see also Apple docs.
+
+    Any `date` related keys will be converted to python
+    :class:`datetime.datetime` object. The quantity and any `date_ms` related
+    keys will be converted to python :class:`int`.
+    """
     __WHITELIST__ = [
         'unique_identifier', 'quantity', 'product_id', 'transaction_id',
         'original_transaction_id', 'is_trial_period',
diff --git a/itunesiap/request.py b/itunesiap/request.py
index b3fbc0b..5b84d83 100644
--- a/itunesiap/request.py
+++ b/itunesiap/request.py
@@ -1,4 +1,4 @@
-
+""":mod:`itunesiap.request`"""
 import json
 import functools
 
@@ -17,9 +17,13 @@ class Request(object):
     """Validation request with raw receipt.
 
     Use `verify` method to try verification and get Receipt or exception.
+    For detail, see also the Apple document: `<https://developer.apple.com/library/content/releasenotes/General/ValidateAppStoreReceipt/Chapters/ValidateRemotely.html>`_.
 
     :param str receipt_data: An iTunes receipt data as Base64 encoded string.
+    :param str password: Only used for receipts that contain auto-renewable subscriptions. Your app's shared secret (a hexadecimal string).
+    :param bool exclude_old_transactions: Only used for iOS7 style app receipts that contain auto-renewable or non-renewing subscriptions. If value is true, response includes only the latest renewal transaction for any subscriptions.
     :param proxy_url: A proxy url to access the iTunes validation url.
+        (It is an attribute of :func:`verify` but misplaced here)
     """
 
     def __init__(
@@ -29,13 +33,17 @@ def __init__(
         self.password = password
         self.exclude_old_transactions = exclude_old_transactions
         self.proxy_url = kwargs.pop('proxy_url', None)
+        if kwargs:  # pragma: no cover
+            raise TypeError(
+                u"__init__ got unexpected keyword argument {}".format(
+                    ', '.join(kwargs.keys())))
 
     def __repr__(self):
         return u'<Request({0}...)>'.format(self.receipt_data[:20])
 
     @property
     def request_content(self):
-        """Build request body for iTunes."""
+        """Instantly built request body for iTunes."""
         request_content = {
             'receipt-data': self.receipt_data,
             'exclude-old-transactions': self.exclude_old_transactions}
@@ -44,9 +52,13 @@ def request_content(self):
         return request_content
 
     def verify_from(self, url, timeout=None, verify_ssl=True):
-        """Try verification from given url.
+        """The actual implemention of verification request.
+
+        :func:`verify` calls this method to try to verifying for each servers.
 
         :param str url: iTunes verification API URL.
+        :param float timeout: The value is connection timeout of the verifying
+            request. The default value is 30.0 when no `env` is given.
         :param bool verify_ssl: SSL verification.
 
         :return: :class:`itunesiap.receipt.Receipt` object if succeed.
@@ -78,10 +90,24 @@ def verify(self, **options):
         verified. The verify_ssl is set to false by default for
         backwards compatibility.
 
-        :param Environment env: Override environment if given
-        :param bool use_production: Override environment value if given
-        :param bool use_sandbox: Override environment value if given
-        :param bool verify_ssl: Override environment value if given
+        See also:
+            - Receipt_Validation_Programming_Guide_.
+
+        .. _Receipt_Validation_Programming_Guide: https://developer.apple.com/library/content/releasenotes/General/ValidateAppStoreReceipt/Chapters/ValidateRemotely.html
+
+        :param itunesiap.environment.Environment env: Override the environment.
+        :param float timeout: The value is connection timeout of the verifying
+            request. The default value is 30.0 when no `env` is given.
+        :param bool use_production: The value is weather verifying in
+            production server or not. The default value is :class:`bool` True
+            when no `env` is given.
+        :param bool use_sandbox: The value is weather verifying in
+            sandbox server or not. The default value is :class:`bool` False
+            when no `env` is given.
+
+        :param bool verify_ssl: The value is weather enabling SSL verification
+            or not. WARNING: DO NOT TURN IT OFF WITHOUT A PROPER REASON. IF YOU
+            DON'T UNDERSTAND WHAT IT MEANS, NEVER SET IT YOURSELF.
 
         :return: :class:`itunesiap.receipt.Receipt` object if succeed.
         :raises: Otherwise raise a request exception.
diff --git a/itunesiap/shortcut.py b/itunesiap/shortcut.py
index a9d506f..dcc05ae 100644
--- a/itunesiap/shortcut.py
+++ b/itunesiap/shortcut.py
@@ -1,19 +1,50 @@
-
+""":mod:`itunesiap.shortcut`"""
 from .request import Request
 
 
 def verify(
         receipt_data, password=None, exclude_old_transactions=False, **kwargs):
-    """Shortcut API for :class:`itunesiap.request.Request`
+    """Shortcut API for :class:`itunesiap.request.Request`.
+
+    See also:
+        - Receipt_Validation_Programming_Guide_.
+
+    .. _Receipt_Validation_Programming_Guide: https://developer.apple.com/library/content/releasenotes/General/ValidateAppStoreReceipt/Chapters/ValidateRemotely.html
+
+    :param str receipt_data: :class:`itunesiap.request.Request` variable.
+        An iTunes receipt data as Base64 encoded string.
+    :param str password: :class:`itunesiap.request.Request` variable. Optional.
+        Only used for receipts that contain auto-renewable subscriptions. Your
+        app's shared secret (a hexadecimal string).
+    :param bool exclude_old_transactions: :class:`itunesiap.request.Request`
+        variable. Optional. Only used for iOS7 style app receipts that contain
+        auto-renewable or non-renewing subscriptions. If value is true,
+        response includes only the latest renewal transaction for any
+        subscriptions.
+
+    :param itunesiap.environment.Environment env: Set base environment value.
+        See :mod:`itunesiap.environment` for detail.
+    :param float timeout: :func:`itunesiap.request.Request.verify` variable.
+        Keyword-only optional. The value is connection timeout of the verifying
+        request. The default value is 30.0 when no `env` is given.
+    :param bool use_production: :func:`itunesiap.request.Request.verify`
+        variable. Keyword-only optional. The value is weather verifying in
+        production server or not. The default value is :class:`bool` True
+        when no `env` is given.
+    :param bool use_sandbox: :func:`itunesiap.request.Request.verify`
+        variable. Keyword-only optional. The value is weather verifying in
+        sandbox server or not. The default value is :class:`bool` False
+        when no `env` is given.
 
-    :param str receipt_data: An iTunes receipt data as Base64 encoded string.
-    :param proxy_url: A proxy url to access the iTunes validation url
-    :param bool use_production: Override environment value if given
-    :param bool use_sandbox: Override environment value if given
-    :param bool verify_ssl: Override environment value if given
+    :param bool verify_ssl: :func:`itunesiap.request.Request.verify` variable.
+        Keyword-only optional. The value is weather enabling SSL verification
+        or not. WARNING: DO NOT TURN IT OFF WITHOUT A PROPER REASON. IF YOU
+        DON'T UNDERSTAND WHAT IT MEANS, NEVER SET IT YOURSELF.
+    :param str proxy_url: Keyword-only optional. A proxy url to access the
+        iTunes validation url.
 
     :return: :class:`itunesiap.receipt.Receipt` object if succeed.
-    :raises: Otherwise raise a request exception.
+    :raises: Otherwise raise a request exception in :mod:`itunesiap.exceptions`.
     """
     proxy_url = kwargs.pop('proxy_url', None)
     request = Request(
diff --git a/setup.py b/setup.py
index 679c16e..541b844 100644
--- a/setup.py
+++ b/setup.py
@@ -42,6 +42,7 @@ def get_readme():
     tests_require=tests_require,
     extras_require={
         'tests': tests_require,
+        'doc': ['sphinx'],
     },
     classifiers=[
         'Intended Audience :: Developers',