In computing, a login session is the period of activity between a user logging in

Logging (computer security)

In computer security, a login or logon is the process by which individual access to a computer system is controlled by identifying and authentifying the user referring to credentials presented by the user.A user can log in to a system to obtain access and can then log out or log off In computer...

 and logging out of a (multi-user) system.

On Unix

Unix

Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...

 and Unix-like

Unix-like

A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....

 operating systems, a login session takes one of two main forms:

• When a textual user interface is used, a login session is represented as a kernel session — a collection of process group
  Process group
  In POSIX-conformant operating systems, a process group denotes a collection of one or more processes. Process groups are used to control the distribution of signals. A signal directed to a process group is delivered individually to all of the processes that are members of the group.Process groups...
  
  s with the logout action managed by a session leader.
• Where an X display manager is employed, a login session is considered to be the lifetime of a designated user process that the display manager invokes.

On Windows NT

Windows NT

Windows NT is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. It was a powerful high-level-language-based, processor-independent, multiprocessing, multiuser operating system with features comparable to Unix. It was intended to complement...

-based systems, login sessions are maintained by the kernel and control of them is within the purview of the Local Security Authority Subsystem Service

Local Security Authority Subsystem Service

Local Security Authority Subsystem Service , is a process in Microsoft Windows operating systems that is responsible for enforcing the security policy on the system. It verifies users logging on to a Windows computer or server, handles password changes, and creates access tokens...

 (LSA). winlogon

Winlogon

In computing, Winlogon is the component of Microsoft Windows operating systems that is responsible for handling the secure attention sequence, loading the user profile on logon, and optionally locking the computer when a screensaver is running...

responds to the secure attention key

Secure attention key

A secure attention key is a special key or key combination to be pressed on a computer keyboard before a login screen must be trusted by a user. The operating system kernel, which interacts directly with the hardware, is able to detect whether the secure attention key has been pressed...

, requests the LSA to create login sessions on login, and terminates all of the processes belonging to a login session on logout.

See also

• Windows NT Startup Process
  Windows NT Startup Process
  The Windows NT startup process is the process by which Windows NT 4.0, Windows 2000, Windows XP and Windows Server 2003 operating systems initialize...
  
  
• Architecture of the Windows NT operating system line
  Architecture of the Windows NT operating system line
  The architecture of Windows NT, a line of operating systems produced and sold by Microsoft, is a layered design that consists of two main components, user mode and kernel mode. It is a preemptive, reentrant operating system, which has been designed to work with uniprocessor and symmetrical multi...
  
  
• Booting
  Booting
  In computing, booting is a process that begins when a user turns on a computer system and prepares the computer to perform its normal operations. On modern computers, this typically involves loading and starting an operating system. The boot sequence is the initial set of operations that the...
  
  
• Master boot record
  Master boot record
  A master boot record is a type of boot sector popularized by the IBM Personal Computer. It consists of a sequence of 512 bytes located at the first sector of a data storage device such as a hard disk...
  
  
• Power-on self-test
  Power-on self-test
  Power-On Self-Test refers to routines run immediately after power is applied, by nearly all electronic devices. Perhaps the most widely-known usage pertains to computing devices...
  
  
• Windows Vista Startup Process
  Windows Vista Startup Process
  The startup process of Windows Vista, Windows Server 2008, Windows 7 and Windows Server 2008 R2 is different from any previous versions of Windows. For Windows Vista, the boot sector loads the Windows Boot Manager , which first looks for an active partition, then accesses the Boot Configuration...
  
  
• BootVis
  BootVis
  BootVis is a computer application that allows PC manufacturers to check how long a Windows XP machine takes to boot, and then to optimize the boot process, sometimes considerably reducing the time required...