This document introduces chat bots and discusses their increasing popularity. It notes that the app boom is over as the top apps are now chat apps, and that people prefer communicating in chat platforms. Chat provides a more natural experience than apps. Advances in AI have made building chat bots more accessible using various machine learning and natural language processing tools. The document then outlines different types of chat bots based on their function and intelligence, and lists popular bot platforms and channels. It concludes with suggestions for further reading on chat bots.