"Ant is a Java based build tool. In theory it is kind of like make without make's wrinkles. Why another build tool when there is already make, gnumake, nmake, jam, and others? Because all of those tools have limitations that Ant's original author couldn't live with when developing software across multiple platforms. Make-like tools are inherently shell based. They evaluate a set of dependencies and then execute commands not unlike what you would issue on a shell. This means that you can easily extend these tools by using or writing any program for the OS that you are working on. However, this also means that you limit yourself to the OS, or at least the OS type such as Unix, that you are working on.
Makefiles are inherently evil as well. Anybody who has worked on them for any time has run into the dreaded tabproblem. "Is my command not executing because I have a space in front of my tab!!!" said the original author of Ant way too many times. Tools like Jam took care of this to a great degree, but still use yet another format to use and remember.
Ant is different. Instead of a model where it is extended with shell based commands, it is extended using Javaclasses. Instead of writing shell commands, the configuration files are XML based calling out a target tree wherevarious tasks get executed. Each task is run by an object which implements a particular Task interface."