computer security Computer security, cybersecurity (cyber security), or information technology security (IT security) is the protection of computer systems and networks from attack by malicious actors that may result in unauthorized information disclosure, t ...

, logging in (or logging on, signing in, or signing on) is the process by which an individual gains

access Access may refer to: Companies and organizations * ACCESS (Australia), an Australian youth network * Access (credit card), a former credit card in the United Kingdom * Access Co., a Japanese software company * Access Healthcare, an Indian BPO se ...

to a

computer system A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations ( computation) automatically. Modern digital electronic computers can perform generic sets of operations known as programs. These prog ...

by identifying and

authenticating Authentication (from ''authentikos'', "real, genuine", from αὐθέντης ''authentes'', "author") is the act of proof (truth), proving an Logical assertion, assertion, such as the Digital identity, identity of a computer system user. In ...

themselves. The

user Ancient Egyptian roles * User (ancient Egyptian official), an ancient Egyptian nomarch (governor) of the Eighth Dynasty * Useramen, an ancient Egyptian vizier also called "User" Other uses * User (computing), a person (or software) using an ...

credentials are typically some form of

username A user is a person who utilizes a computer or network service. A user often has a user account and is identified to the system by a username (or user name). Other terms for username include login name, screenname (or screen name), accoun ...

and a matching

password A password, sometimes called a passcode (for example in Apple devices), is secret data, typically a string of characters, usually used to confirm a user's identity. Traditionally, passwords were expected to be memorized, but the large number of ...

, and these credentials themselves are sometimes referred to as ''a'' login (or logon, sign-in, sign-on).Oxford Dictionaries
definition of ''login''.
detail and definition of ''login'' and ''logging in''. In practice, modern secure systems often require a second factor such as

email Electronic mail (email or e-mail) is a method of exchanging messages ("mail") between people using electronic devices. Email was thus conceived as the electronic ( digital) version of, or counterpart to, mail, at a time when "mail" meant ...

SMS Short Message/Messaging Service, commonly abbreviated as SMS, is a text messaging service component of most telephone, Internet and mobile device systems. It uses standardized communication protocols that let mobile devices exchange short text ...

confirmation for extra security.

Social login Social login is a form of single sign-on using existing information from a social networking service such as Facebook, Twitter or Google, to sign into a third party website instead of creating a new login account specifically for that website. It i ...

allows a user to use existing user credentials from a

social networking service A social networking service or SNS (sometimes called a social networking site) is an online platform which people use to build social networks or social relationships with other people who share similar personal or career content, interests, act ...

to sign in to or create an account on a new website. When access is no longer needed, the user can log out (log off, sign out or sign off).

Procedure

Logging in is usually used to enter a specific page, website or application, which trespassers cannot see. Once the user is logged in, the login token may be used to track what actions the user has taken while connected to the site. Logging out may be performed explicitly by the

taking some actions, such as entering the appropriate

command Command may refer to: Computing * Command (computing), a statement in a computer language * COMMAND.COM, the default operating system shell and command-line interpreter for DOS * Command key, a modifier key on Apple Macintosh computer keyboards * ...

or clicking a

website A website (also written as a web site) is a collection of web pages and related content that is identified by a common domain name and published on at least one web server. Examples of notable websites are Google Search, Google, Facebook, Amaz ...

link label as such. It can also be done implicitly, such as by the user powering off his or her workstation, closing a

web browser A web browser is application software for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's screen. Browsers are used on ...

window, leaving a website, or not refreshing a website within a defined period. A login page may have a return URL parameter, which specifies where to redirect back after logging in or out. For example, it is returnto= on this site. In the case of websites that use

cookies A cookie is a baked or cooked snack or dessert that is typically small, flat and sweet. It usually contains flour, sugar, egg, and some type of oil, fat, or butter. It may include other ingredients such as raisins, oats, chocolate chips, nuts ...

to track sessions, when the user logs out, session-only cookies from that site will usually be deleted from the user's computer. In addition, the server invalidates any associations with the session, thereby making any session-handle in the user's cookie store useless. This feature comes in handy if the user is using a

public computer A public computer (or public access computer) is any of various computers available in public areas. Some places where public computers may be available are libraries, schools, or dedicated facilities run by government. Public computers share simi ...

or a computer that is using a public wireless connection. As a security precaution, one should not rely on implicit means of logging out of a system, especially not on a public computer; instead, one should explicitly log out and wait for the confirmation that this request has taken place. Logging out of a computer, when leaving it, is a common security practice preventing unauthorised users from tampering with it. There are also people who choose to have a password-protected

screensaver A screensaver (or screen saver) is a computer program that blanks the display screen or fills it with moving images or patterns when the computer has been idle for a designated time. The original purpose of screensavers was to prevent phosphor ...

set to activate after some period of inactivity, thereby requiring the user to re-enter his or her login credentials to unlock the screensaver and gain access to the system. There can be different methods of logging in that may be via image, fingerprints, eye scan, password (oral or textual input), etc.

History and etymology

The terms became common with the

time sharing In computing, time-sharing is the sharing of a computing resource among many users at the same time by means of multiprogramming and multi-tasking.DEC Timesharing (1965), by Peter Clark, The DEC Professional, Volume 1, Number 1 Its emergence a ...

systems of the 1960s and

Bulletin Board System A bulletin board system (BBS), also called computer bulletin board service (CBBS), is a computer server running software that allows users to connect to the system using a terminal program. Once logged in, the user can perform functions such as ...

s (BBS) in the 1970s. Early home computers and

personal computer A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or tec ...

s did not generally require them until

Windows NT Windows NT is a proprietary graphical operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems sc ...

OS/2 OS/2 (Operating System/2) is a series of computer operating systems, initially created by Microsoft and IBM under the leadership of IBM software designer Ed Iacobucci. As a result of a feud between the two companies over how to position OS/2 ...

and

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which ...

in the 1990s. The noun ''login'' comes from the verb ''(to) log in'' and by analogy with the verb ''to clock in''. Computer systems keep a ''

log Log most often refers to: * Trunk (botany), the stem and main wooden axis of a tree, called logs when cut ** Logging, cutting down trees for logs ** Firewood, logs used for fuel ** Lumber or timber, converted from wood logs * Logarithm, in mathe ...

'' of users' access to the system. The term "log" comes from the

chip log A chip log, also called common log, ship log, or just log, is a navigation tool mariners use to estimate the speed of a vessel through water. The word ''knot'', to mean nautical mile per hour, derives from this measurement method. History All ...

historically used to record distance travelled at sea and was recorded in a

ship's log A logbook (a ship's logs or simply log) is a record of important events in the management, operation, and navigation of a ship. It is essential to traditional navigation, and must be filled in at least daily. The term originally referred to a bo ...

log book A logbook (or log book) is a record used to record states, events, or conditions applicable to complex machines or the personnel who operate them. Logbooks are commonly associated with the operation of aircraft, nuclear plants, particle accelera ...

. To ''sign in'' connotes the same idea, but it's based on the analogy of manually signing a log book or visitors book. While there is no agreed difference in meaning between the three terms (''login'', ''logon'' and ''sign''-''in''), different technical communities tend to prefer one over another – Unix, Novell, Linux and Apple typically use ''login'', and Apple's

style guide A style guide or manual of style is a set of standards for the writing, formatting, and design of documents. It is often called a style sheet, although that term also has multiple other meanings. The standards can be applied either for gene ...

says ''"Users log in to a file server (not log on to)...".'' By contrast, Microsoft's style guides traditionally suggested the opposite and prescribed ''log on'' and ''logon''. In the past, Microsoft reserved ''sign-in'' to when accessing the Internet,"Use log on or log on to... Do not use log in, login", 2004, ''Manual of Style for Technical Publications'', 3rd edition, p. 295, Microsoft.com. but from

Windows 8 Windows 8 is a major release of the Windows NT operating system developed by Microsoft. It was Software release life cycle#Release to manufacturing (RTM), released to manufacturing on August 1, 2012; it was subsequently made available for downl ...

onward it has moved to the ''sign-in'' terminology for local authentication."Sign in to or out of Windows"
Microsoft.com.

References

{{Authority control Authentication methods User interfaces Computer access control

Procedure

History and etymology

See also

References