Through this tutorial, let's go to the discovery of this amazing NLP library under the sweet name of Natural Language Toolkit (NLTK). It's a toolkit for creating programs for text analysis. This set was originally created by Steven Bird and Edward Loper, in connection with courses in computational linguistics at the University of Pennsylvania in 2001. There is a learning manual for this set titled Natural Language Processing with Python ( in English): http://www.nltk.org/book/