Also, please see the main wiki page.
The latest release is ANTLR 4.1 as of June 30, 2013
Copyright © 2012, The Pragmatic Bookshelf. Pragmatic Bookshelf grants a nonexclusive, irrevocable, royalty-free, worldwide license to reproduce, distribute, prepare derivative works, and otherwise use this contribution as part of the ANTLR project and associated documentation.
This text was copied with permission from the The Definitive ANTLR 4 Reference, though it is being morphed over time as the tool changes. Links in the documentation refer to various sections of the book but have been redirected to the general book page on the publisher's site. You should also consider reading the following books:
This documentation is a reference and summarizes grammar syntax and the key semantics of ANTLR grammars. The source code for all examples in the book, not just this chapter, are free at the publisher's website.