Editing Maintainability (section)

== Usage in different fields ==
=== Engineering ===
In [[engineering]], maintainability is the ease with which a product can be maintained to:
* correct defects or their cause,
* [[Repairability|Repair]] or replace faulty or worn-out components without having to replace still working parts,
* prevent unexpected working conditions,
* maximize a product's useful life,
* maximize efficiency, reliability, and safety,
* meet new [[requirements]],
* make future maintenance easier, or
* cope with a changing environment.

In some cases, maintainability involves a system of [[continuous improvement]] - learning from the past to improve the ability to maintain systems, or improve the reliability of systems based on maintenance experience.

=== Telecommunication ===
In [[telecommunications]] and several other engineering fields, the term maintainability has the following meanings:

* A characteristic of design and installation, expressed as the probability that an item will be retained in or restored to a specified condition within a given period of [[time]], when the [[repair and maintenance|maintenance]] is performed by prescribed procedures and resources.
* The ease with which maintenance of a [[functional unit]] can be performed by prescribed requirements.

=== Software ===
In [[software engineering]], these activities are known as [[software maintenance]] (cf. [[ISO/IEC 9126]]). Closely related concepts in the software engineering domain are evolvability, modifiability, [[technical debt]], and [[code smell]]s.

The maintainability index is calculated with certain formulae from [[Lines of code|lines-of-code measures]], [[McCabe Measure|McCabe measures]] and [[Halstead complexity measures]].

The measurement and tracking of maintainability are intended to help reduce or reverse a system's tendency toward "code entropy" or degraded integrity, and to indicate when it becomes cheaper and/or less risky to rewrite the code than it is to change it.

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