• News - NLTK development has moved to GitHub [October 2011], Version 2.0.1rc1 released [April 2011], NLTK Cookbook by Jacob Perkins [December 2010], NLTK book in third printing [November 2010], Japanese translation of NLTK book published [November 2010]
• Code - functionality provided by NLTK in over 100,000 lines of Python code, distributed under the Apache License
  
• Data - ~60 corpora, grammar collections, and trained models that come with NLTK
• Quotes - what people have said about NLTK

Getting Started

• Documentation - book, articles, guides, reviews
• Download - instructions for downloading and installing Python and NLTK on all platforms
• Getting Started - simple things to try, including NLTK's demonstrations
• Subscribe - sign up for important announcements - approx 1 post per month

Getting Help

• FAQ - answers to frequently asked questions
• HOWTO - guides for a variety of NLTK packages, including many examples
• User forum - mailing list for discussion amongst NLTK users
• Chatroom - #nltk on irc.freenode.net (not often staffed)
  

Software

• API Documentation - complete documentation of all NLTK modules
• Source - browse the Python source code
• github - the home of the NLTK development work (submit a feature request or bug report)
• People - the NLTK development team

Education and Research

• Courses - ~100 courses in 23 countries using NLTK (artificial intelligence, computational linguistics, information retrieval, machine learning)
• Projects - ideas for student projects
• Teaching - information for instructors teaching courses using NLTK
• Research - hundreds of research papers that mention or use NLTK, via Google Scholar

Donate! NLTK is free.  If you find it useful, please consider donating to NLTK via PayPal.  We use donations to fund summer projects for students to add useful new functionality to NLTK.