NLTK
NLTK (Natural Language Toolkit) is a leading platform for building Python programs to work with human language data. It offers easy-to-use interfaces, text processing libraries, and wrappers for industrial-strength NLP libraries. NLTK's strengths include its wide range of features such as classification, tokenization, stemming, tagging, parsing, and semantic reasoning. The platform is suitable for linguists, engineers, students, educators, researchers, and industry users. NLTK is a free, open-source, community-driven project supporting Windows, Mac OS X, and Linux. However, users should note that while powerful, NLTK may have a steep learning curve, especially for NLP beginners.