Apache HttpClient is a popular Java library used for making HTTP requests. It simplifies the process of sending and receiving data over the web, allowing developers to interact with web services easily. With features like connection management, cookie handling, and support for various HTTP methods, it provides a robust solution for web communication. The library is part of the Apache Software Foundation and is designed to be flexible and efficient. It supports both synchronous and asynchronous operations, making it suitable for a wide range of applications, from simple web clients to complex enterprise systems.