You can go to the link and select the latest version for your OS i.e.
In order to install NLTK, we must have Python installed on our computers.
Natural Language Toolkit - Useful Resources.Natural Language Toolkit - Text Classification.Natural Language Toolkit - Transforming Trees.Natural Language Toolkit - Transforming Chunks.Natural Language Toolkit - More NLTK Taggers.Natural Language Toolkit - Combining Taggers.Natural Language Toolkit - Unigram Tagger.Natural Language Toolkit - Word Replacement.Training Tokenizer & Filtering Stopwords.