Editing Web server (section)

===== Program or module processing =====
An external program or an internal module (''processing unit'') can execute some sort of application function that may be used to get data from or to store data to one or more [[Content repository|data repositories]], e.g.:{{citation needed|date=November 2021}}
* files (file system);
* [[database]]s (DBs);
* other sources located in local computer or in other computers.

A ''processing unit'' can return any kind of web content, also by using data retrieved from a data repository, e.g.:{{citation needed|date=November 2021}}
* a document (e.g. [[HTML]], [[XML]], etc.);
* an image;
* a video;
* structured data, e.g. that may be used to update one or more values displayed by a dynamic page ([[DHTML]]) of a [[web interface]] and that maybe was requested by an [[XMLHttpRequest]] [[API]] (see also: [[Dynamic web page|dynamic page]]).

In practice whenever there is content that may vary, depending on one or more parameters contained in client request or in configuration settings, then, usually, it is generated dynamically.