The acronym SAML stands for Security Assertion Markup Language. It is an open standard used for exchanging authentication and authorization data between an Identity Provider (IdP) and a Service Provider (SP). SAML facilitates Single Sign-On (SSO) capabilities, allowing users to log in once and gain access to multiple applications or services without re-entering credentials. This streamlines the user experience and improves security by reducing the chances of password fatigue and related vulnerabilities, making it a vital component in modern web security architectures.