Natural Language Processing (sometimes referred to simply as NLP) is an area of computer science that is designing systems which represent human speech patterns. These might be either verbal or written but are designed in such a way that the content is is indistinguishable from actual human speech.
NLP uses neural networks, artificial intelligence and machine learning in order to help computers recognise human speech, process that speech into meaning, and then generate speech responses. This technology is already in widespread use, form Siri in iPhones to the Google and Amazon home devices.