Ant is a Java-based build tool that is used to automate software build processes. It uses XML configuration files to specify targets that call tasks to execute actions like compiling, testing, packaging, and deploying. Some key benefits of Ant include its ability to streamline builds, run tasks in parallel, and manage dependencies between tasks. The document provides examples of using Ant tasks to clean, run code sniffing and unit tests, generate documentation, and copy files to a test server.