In the modern era of technological peregrination, artificial intelligence (AI) is one of the most interesting fields of research and language is the most compelling manifestation of intelligence. In this context, natural language processing (NLP) stands as a popular field of research in current days. Basically, NLP is employed to allow the machines of how humans being speaks and basically aimed at analyzing the text. Moreover, NLP is normally employed for text mining (TM), machine translation, automated question answering, etc. Such human-computer interaction enables real-world applications such as sentiment analysis, automatic text summarization, topic extraction, stemming, machine translation, etc. This chapter further discusses the two basic aspects like natural language understanding (NLU) and natural language generation (NLG) that deal with NLU and generation respectively. Further, the current chapter throws light on various aspects of text processing like: morphological analysis, syntax analysis, semantic analysis, lexical analysis, etc.