This document discusses chatbots and the key technologies behind them. It describes how chatbots are integrated into messaging platforms and examines some of the advantages they provide like low development costs and push notifications. The document outlines two types of chatbots - rule-based and AI-based - and discusses some of the capabilities and challenges of early chatbot technologies like intent recognition and entity extraction. It provides examples of how natural language processing, machine learning, and deep learning are used to power chatbot functions.