Editing Software (section)

==Types==
{{See also|Software categories}}

[[File:Operating system placement (software).svg|thumb|upright|A diagram showing how the [[User (computing)|user]] interacts with [[application software]] on a typical [[desktop computer]]. The application software layer interfaces with the [[operating system]], which in turn communicates with the [[computer hardware|hardware]]. The arrows indicate information flow.]]
There are two main types of software:
* [[Operating system]]s are "the [[abstraction layer|layer of software]] that manages a computer's resources for its users and their [[Application software|application]]s".{{sfn|Anderson|Dahlin|2014|p=6}} There are three main purposes that an operating system fulfills:{{sfn|Anderson|Dahlin|2014|p=7}}
**Allocating resources between different applications, deciding when they will receive [[central processing unit]] (CPU) time or space in [[computer memory|memory]].{{sfn|Anderson|Dahlin|2014|p=7}}
**Providing an interface that abstracts the details of accessing [[Computer hardware|hardware]] details (like physical memory) to make things easier for programmers.{{sfn|Anderson|Dahlin|2014|p=7}}{{sfn|Tanenbaum|Bos|2023|p=5}}
**Offering common services, such as an interface for accessing network and disk devices. This enables an application to be run on different hardware without needing to be rewritten.{{sfn|Anderson|Dahlin|2014|pp=7, 9, 13}}
* [[Application software]] runs on top of the operating system and uses the computer's resources to perform a task.{{sfn|Anderson|Dahlin|2014|pp=6-7}} There are many different types of application software because the range of tasks that can be performed with modern computers is so large.{{sfn|Jones|2014|p=121}} Applications account for most software{{sfn|Tracy|2021|p=66}} and require the [[Operating environment|environment]] provided by an operating system, and often other applications, in order to function.{{sfn|Tracy|2021|p=72}}

[[File:Comparison of on-premise, IaaS, PaaS, and SaaS.png|thumb|Comparison of on-premise hardware and software, [[infrastructure as a service]] (IaaS), [[platform as a service]] (PaaS), and [[software as a service]] (SaaS)|upright=2.4|center]]
Software can also be categorized by how it is [[software deployment|deployed]]. Traditional applications are purchased with a perpetual [[software license|license]] for a specific version of the software, downloaded, and run on hardware belonging to the purchaser.{{sfn|O'Regan|2022|p=386}}  The rise of [[the Internet]] and [[cloud computing]] enabled a new model, [[software as a service]] (SaaS),{{sfn|Campbell-Kelly|Garcia-Swartz|2015|pp=156-157}} in which the provider hosts the software (usually built on top of rented [[infrastructure as a service|infrastructure]] or [[platform as a service|platform]]s){{sfn|Rosati |Lynn|2020|p=23}} and provides the use of the software to customers, often in exchange for a [[subscription fee]].{{sfn|O'Regan|2022|p=386}} By 2023, SaaS products—which are usually delivered via a [[web application]]—had become the primary method that companies deliver applications.{{sfn|Watt|2023|p=4}}