Language, ability to speak, write and communicate is one of the most fundamental aspects of human behavior. As the study of human-languages developed the concept of communicating with non-human devices was investigated. This is the origin of natural language processing (NLP). The idea of natural language processing is to design and build a computer system that will analyze, understand and generate natural human-languages. Natural language communication with computers has long been a major goal of artificial intelligence, both for the information it can give about intelligence in general, and for practical utility. There are many applications of natural language processing developed over the years. They can be mainly divided into two parts as follows.

1. Text-based applications
this involves applications such as searching for a certain topic or a keyword in a data base, extracting information from a large document, translating one language to another or summarizing text for different purposes.

2. Dialogue based applications
Some of the typical examples of this are answering systems that can answer questions, services that can be provided over a telephone without an operator, teaching systems, voice controlled machines (that take instructions by speech) and general problem solving systems.

• N-gram statistical language models for Persian language extraction
• Persian language grammar rules extraction
• Preparing Persian language lexicon
• More frequent words of certain topics extraction