Signing in and gaining access to a computer, local network server, Web server or to a particular account. The login identifies the user, and a username and password are typically required. Although a password is not mandatory for a user's own computer or mobile device, it is always recommended. See password
Variations and Spelling
Also called "log on," "sign in" or "sign on," the action of logging in (verb) is spelled with two words: "please log in." However, the process (noun) is one word: "the login." In contrast, to exit the system is to "log out," "log off," "sign out" or "sign off." For example: "be sure to log in" and "her login name is allison77."
Right and Wrong Usage
The verb is two words; the noun is one. Many user interface designers are unaware of this distinction.