Login is the process of gaining access to a computer system, website, or app by proving who you are. When you log in to your school's computer, you typically enter a username and password that identify you and show you're allowed to use the system.

You might log in to an email account, a gaming platform, or a school website. Each login usually requires credentials: information only you should know, like a password or PIN. Some systems use other methods, like fingerprints or facial recognition, but they're all different forms of logging in.

The word works as both a noun (“Enter your login information”) and a verb in two-word form (“Log in to your account”). People sometimes write it as one word when using it as a verb (login instead of log in), though traditional usage keeps the verb form as two words.

The opposite is logout or log out: the process of ending your session and making sure others can't access your account.