While many technical professionals claim to know and understand OAuth, reality often suggests otherwise. Implementing the proper grant types and the required flows while securely protecting your secrets is challenging at best and catastrophic at worst. Fundamentally, professionals often struggle with OAuth because they misunderstand what it is, what use cases it is particularly good and bad at, and how to integrate it smoothly and safely into their systems. In this course, review the basics of OAuth 2.0 and OpenID Connect, and learn how to use them to authenticate your applications. Learn about tokens, scopes, and claims; OAuth flows; common security considerations; and more.