From the project description:

Address Book Project is an application written in C language. It keeps track of names and telephone/mobile numbers and e-mail addresses. It is a console based application which uses standard I/O for adding and deleting contact names, phone numbers and e-mail addresses, searching names and associated numbers and email addresses, updating numbers and email addresses, and deleting contacts. This project will make you implement some important features of C programming which includes command line arguments, input parsing, file operations etc. Since this project is part of the C programming module, it will not use any Abstract Data Type (ADTs) like linked lists, rather you will be using existing C programming features mentioned above. As an advanced level this project can be implemented with ADTs and much more sophisticated search algorithms by achieving much optimal resource usage. By implementing this project in a hands-on way you will be able to build a firm understanding on the code C programming concepts and how to apply them on a use case like address book.

If you're a contributor, to get started see the following links:

Project Outline: https://www.emertxe.com/embedded-systems/c-programming/c-projects/address-book-c/

Project Specs Doc: https://github.com/tsmaz/AddressBook/blob/main/address_book.pdf

For current features in development and issues you can claim, see: https://github.com/tsmaz/AddressBook/issues