Pattern is a web mining module for the Python programming language. It bundles tools for data retrieval (Google + Twitter + Wikipedia API, web spider, HTML DOM parser), text analysis (rule-based shallow parser, WordNet interface, syntactical + semantical n-gram search algorithm, tf-idf + cosine similarity + LSA metrics), clustering and classification (k-means, k-NN, SVM), and data visualization (graph networks). The module is bundled with 30+ examples and 350+ unit tests. Pattern is written for Python 2.5+ (no support for Python 3 yet). The source code is licensed under BSD and available from http://www.clips.ua.ac.be/pages/pattern.