What type of authentication relies solely on a username and password?

Single factor authentication is a method that relies solely on one category of credentials for verifying a user's identity, which, in this context, is a username and password. This approach is straightforward and commonly used across many systems and applications.

In single factor authentication, the user provides just these two pieces of information: the username to identify the user account and the password to verify that the individual attempting to log in is indeed the rightful owner of that account. This simplicity is a hallmark of single factor authentication, but it also highlights potential security vulnerabilities, such as susceptibility to password theft, weak passwords, or brute force attacks.

Other forms of authentication, such as two-factor and multifactor authentication, introduce additional layers of security by requiring more than just a username and password. Two-factor authentication typically adds a second method of verification, such as a mobile device code, while multifactor authentication could involve multiple methods from different categories, thus providing enhanced security. Dynamic authentication refers to factors changing based on context (like location or time), rather than relying solely on a stable username and password.