Single Sign On, or SSO, is probably a phrase or acronym that you have seen a lot. To understand what it is in the most basic sense, consider this analogy: the internet is like a shopping mall, and each storefront a domain. Now, each time you enter a different store, you are immediately asked to provide your identity, and again asked to confirm that identity upon checkout. After visiting more than a couple stores, this process would probably get pretty frustrating, right?
SSO is an access mechanism that allows users to securely authenticate with multiple applications and websites by logging in only once. It permits a user to use one set of login credentials (e.g., name and password) to access multiple applications, and furthermore helps to mitigate the management of multiple usernames and passwords.
A well known example online is the “Login with Facebook” button that you see when accessing various websites. Instead of going through the process of creating a new password and filling out personal information, a user can just create and access an account using their existing social media credentials.