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.
Finger print login, a recent banking security application
IBM AIX Version 4 console login prompt
Multi-factor authentication
Multi-factor authentication is an electronic authentication method in which a user is granted access to a website or application only after successfully presenting two or more pieces of evidence to an authentication mechanism. MFA protects personal data—which may include personal identification or financial assets—from being accessed by an unauthorized third party that may have been able to discover, for example, a single password.
Hardware authentication security keys
RSA SecurID token, an example of a disconnected token generator
A USB security token