OpenID is an open standard that allows users to log into multiple websites using a single digital identity. Instead of creating separate usernames and passwords for each site, users can authenticate themselves through a trusted provider, such as Google or Facebook. This simplifies the login process and enhances security by reducing the number of passwords a user needs to remember. When a user wants to access a site that supports OpenID, they are redirected to their chosen provider to verify their identity. Once authenticated, they are sent back to the original site, where they can access their account seamlessly. This system promotes convenience and helps protect user information.