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''Scalability'' is the capability of a system, network, or process to handle a growing amount of work, or its potential to be enlarged in order to accommodate that growth. For example, it can refer to the capability of a system to increase its total output under an increased load when resources (typically hardware) are added. An analogous meaning is implied when the word is used in an economic context, where scalability of a company implies that the underlying business model offers the potential for economic growth within the company. Scalability, as a property of systems, is generally difficult to define〔See for instance, and 〕 and in any particular case it is necessary to define the specific requirements for scalability on those dimensions that are deemed important. It is a highly significant issue in electronics systems, databases, routers, and networking. A system whose performance improves after adding hardware, proportionally to the capacity added, is said to be a ''scalable system''. An algorithm, design, networking protocol, program, or other system is said to ''scale'' if it is suitably efficient and practical when applied to large situations (e.g. a large input data set, a large number of outputs or users, or a large number of participating nodes in the case of a distributed system). If the design or system fails when a quantity increases, it ''does not scale''. In practice, if there are a large number of things () that affect scaling, then resource requirements (for example, algorithmic time-complexity) must grow less than as increases. An example is a search engine, that must scale not only for the number of users, but for the number of objects it indexes. Scalability refers to the ability of a site to increase in size as demand warrants. The concept of scalability is desirable in technology as well as business settings. The base concept is consistent the ability for a business or technology to accept increased volume without impacting the contribution margin (= revenue − variable costs). For example, a given piece of equipment may have a capacity for 1–1000 users, while beyond 1000 users additional equipment is needed or performance will decline (variable costs will increase and reduce contribution margin). ==Measures== Scalability can be measured in various dimensions, such as: * ''Administrative scalability'': The ability for an increasing number of organizations or users to easily share a single distributed system. * ''Functional scalability'': The ability to enhance the system by adding new functionality at minimal effort. * ''Geographic scalability'': The ability to maintain performance, usefulness, or usability regardless of expansion from concentration in a local area to a more distributed geographic pattern. * ''Load scalability'': The ability for a distributed system to easily expand and contract its resource pool to accommodate heavier or lighter loads or number of inputs. Alternatively, the ease with which a system or component can be modified, added, or removed, to accommodate changing load. * ''Generation scalability'' refers to the ability of a system to scale up by using new generations of components. Thereby, ''heterogeneous scalability'' is the ability to use the components from different vendors. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Scalability」の詳細全文を読む スポンサード リンク
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