||This article relies largely or entirely upon a single source. (October 2010)|
||This article may contain original research. (October 2010)|
In computing, a service pack or SP (in short SP) or a feature pack (FP) comprises a collection of updates, fixes, or enhancements to a software program delivered in the form of a single installable package. Companies often release a service pack when the number of individual patches to a given program reaches a certain (arbitrary) limit. Installing a service pack is easier and less error-prone than installing many individual patches, even more so when updating multiple computers over a network.
Incremental and cumulative SPs 
A service pack can be "incremental", meaning it only contains the updates that were not present in the previous service packs, or it can be cumulative, which means it includes the contents of all its predecessors. In the case of Microsoft's products, an incremental update was called a service release. For example, Office 2000 must be upgraded to service release 1 (SR‑1) before one can install SP2.
As of 2013[update] recent service packs for Microsoft Windows are cumulative. This means that the problems that are fixed in a service pack are also fixed in later service packs. For example, Windows XP SP3 contains all the fixes that are included in Windows XP Service Pack 2 (SP2).
Office XP, 2003, and 2007 service packs have been cumulative.
Impact on installation of additional software components 
Application service packs replace existing files with updated versions that typically fix bugs or close security holes. If, at a later time, additional components are added to the software using the original media, there is a risk of accidentally mixing older and updated components. Depending on the operating system and deployment methods, it may then be necessary to manually reinstall the service pack after each such change to the software. This was, for example, necessary for Windows NT service packs; however, from Windows 2000 onwards, Microsoft redirected setup programs to use updated service pack files instead of files from original installation media in order to prevent manual reinstalls.
See also 
- Adaptation Kit Update
- Apple Software Update
- IBM Program temporary fix
- Point release
- Slipstream (computing)
- Software release life cycle
- Windows Update
- One counterexample is Microsoft SQL Server 2000 Service Pack 3a
- Knowledgebase, Microsoft. "List of fixes included in Windows XP SP3". Microsoft. Retrieved 22 November 2012.
- Not Necessary to Reinstall Windows 2000 Service Packs After System State Changes
- Microsoft Support Lifecycle (includes Microsoft's service pack policy)
- Microsoft Service Packs
- Windows Service Packs
- List of fixes that are included in Windows XP Service Pack 3