Quick Answer: In computer security, logging in is the process by which an individual gains access to a computer system or program by identifying and authenticating themselves. Typically, user credentials consist of a username and a password. These credentials themselves are sometimes referred to as a login. Modern secure systems often require a second factor, such as email or SMS confirmation for extra security. Social login allows a user to use an existing cell phone number or user credentials from another email or social networking service to sign in or create an account on a new website. When access is no longer needed, the user can log out, log off, sign out or sign off.