OAuth is an open standard/specification for achieving authorization. It works over HTTPS, and anyone can implement the specification. The specification works by validating access tokens, and then authorizes devices, APIs, servers, and so on.
Two versions—namely OAuth 1.0 (https://tools.ietf.org/html/rfc5849) and OAuth 2.0 (https://tools.ietf.org/html/rfc6749)—exist. These versions are not compatible with each other and cannot work together. We will use version 2.0 and it will be referred to as OAuth 2.0, throughout this book.
SAML, released in 2005, is a good fit for the web browser (still). But with modern web and native applications (mobile devices), SAML required a serious overhaul, and that's when OAuth came in. Single Page Applications (SPAs) and native applications are different from traditional server-side...
