A login is a set of credentials used to authenticate a user. Most often, these consist of a username and password. However, a login may include other information, such as a PIN number, passcode, or passphrase. Some logins require a biometric identifier, such as a fingerprint or retina scan.

Logins are used by websites, computer applications, and mobile apps. They are a security measure designed to prevent unauthorized access to confidential data. When a login fails (i.e, the username and password combination does not match a user account), the user is disallowed access. Many systems block users from even trying to log in after multiple failed login attempts.

Examples of logins include:

  • Operating system login – Windows and Mac systems can be configured to require a login in order to use the computer after it is turned on or woken from sleep mode. A login may also be required to install software or modify system files.
  • Website login – Webmail interfaces, financial websites, and many other sites require a username and password in order to access account information.
  • App store login – App stores like Google Play and Apple's App Store require a login to download mobile apps, music, and other files.
  • FTP login – file transfer programs often require a login in order to browse, send, and receive files from an FTP server.
  • Router login – Wired and wireless routers typically require an administrator login to modify the settings.

At a basic level, logins make user accounts possible. Most systems require unique usernames, which ensures every user's login is different. On a more advanced level, logins provide a security layer between unsecured and secure activity. Once a user logs in to a secure website, for example, all data transfers are typically encrypted. This prevents other systems from viewing or recording the data transferred from the server.

NOTE: Login is technically a noun, not a verb. To enter a username and password is to "log in," "sign in," or "log on" (two words).

Updated August 12, 2017 by Per C.

quizTest Your Knowledge

What process scrambles data to make it unreadable without a special key?

Correct! Incorrect!     View the Encryption definition.
More Quizzes →

The Tech Terms Computer Dictionary

The definition of Login on this page is an original definition written by the TechTerms.com team. If you would like to reference this page or cite this definition, please use the green citation links above.

The goal of TechTerms.com is to explain computer terminology in a way that is easy to understand. We strive for simplicity and accuracy with every definition we publish. If you have feedback about this definition or would like to suggest a new technical term, please contact us.

Sign up for the free TechTerms Newsletter

How often would you like to receive an email?

You can unsubscribe or change your frequency setting at any time using the links available in each email.

Questions? Please contact us.