A general overview of login:
A login is an act of logging in (also referred to as logging on, signing on, or signing in) to the computer, system, or database via authenticating and identifying a person. In computer security, login is used to gain individual access to a network or area, requiring proper authorization.
The Brief History and Terminology of Login
In the 1970s, the terminology of the Login session became known via Bulletin Board Systems (BBS). Early personal/home computers did not them Login until OS/2, Windows NT, and Linux in the 1990s. The term ‘log’ comes from the ‘chip log’ used to record distance travel at the seaside, later recorded in a logbook or a ship's log.
A user is a person who operates a network, computer, or another device service. The user has an account identified to the system by credentials such as username, password, login name, screen name, account name, nickname, and handle.
Login credentials are used to authenticate a user. After enrolling credentials, a user should log in (logon, sign-in, sign-on), and the system allows access to some of the user's private resources, which can be computer, web application, mobile application, etc. When access is no longer needed, log out (log off, sing-off, or sing out) must be done. If a user leaves the system without log out, another user of the computer or browser can easily access the private information, files, and other materials available on the account.
Logging in is used to enter a specific website or application that can not be seen by trespassers. Logging out can be performed explicitly and implicitly. By clicking a website link label or entering the proper command, the user logs out explicitly. However, by powering off the user's workstation, closing a web browser window, or not refreshing a website user logs out implicitly.
The modern security systems for extra security and account protection often requires a second-factor authorization via SMS or email confirmation. By adding two-factor authentication, an account is secured by the system.
If the system notices an attempted login from another browser or device, from which you have not logged in before, the system will not allow login unless you receive a verification code via SMS or email push notification. For instance, when the user enters a username and password to gain access for the private account, an authentication code is sent to the user's mobile device or to an email (It is optional, the user can decide which way is convenient for verification). As soon as the verification code is received, the user enters it to log into the system, computer, or application.