This document discusses natural language processing and machine translation. It describes natural language processing as a field concerned with interactions between computers and human languages. It then lists some common NLP applications like question answering, text categorization, and machine translation. The document discusses rule-based and statistical approaches to machine translation and some issues in machine translation like word order differences between languages and ambiguity. It also briefly describes some existing machine translation systems like Systran, Bing Translator, and Google Translator.