Natural language processing (NLP) is the convergence of artificial intelligence (AI) and linguistics. It is used to make the computers understand the words or statements that are written in human languages. NLP has been developed for making the work and communication with the computer easy and satisfying. As all the computer users cannot be well known by the specific languages of machines so NLP works better with the users who cannot have time for learning the new languages of machines. We can define language as a set of rules or symbols. Symbols are combined to convey the information. They are tyrannized by the set of rules. NLP is classified into two portions that are natural language understanding and natural language generation which evolves the tasks for understanding and generating the text.