Packages for common geometric calculations including the ROS transform library, "tf". Also includes ROS bindings for "bullet" physics engine and "kdl" kinematics/dynamics package.
ROS communications-related packages, including core client libraries (roscpp, rospy, roslisp) and graph introspection tools (rostopic, rosnode, rosservice, rosparam).
Provides a standardized interface for interfacing with preemptable tasks. Examples of this include moving the base to a target location, performing a laser scan and returning the resulting point cloud, detecting the handle of a door, etc.
Allows one to create "nodelets" -- ROS node-like entities that run within the same process so as to avoid IPC and serialization overhead
ROS-independent library for dynamic class (i.e. plugin) introspection and loading from runtime libraries
Maintains a bond (i.e. heart beat ) between ROS nodes and provides feedback when the bond is broken
Allows you to publish the state of a robot (i.e the position of its base and all joints) via the "tf" transform library
Commonly used messages in ROS. Includes messages for actions (actionlib_msgs), diagnostics (diagnostic_msgs), geometric primitives (geometry_msgs), robot navigation (nav_msgs), and common sensors (sensor_msgs), such as laser range finders, cameras, point clouds.
Contains packages for modeling various aspects of robot information, specified in the Xml Robot Description Format (URDF). The core package of this stack is urdf, which parses URDF files, and constructs an object model (C++) of the robot.
Package used to retrieve resources of different kinds, e.g. http://, file://, the ROS specific package://, etc.