Development guidelines

The mw>Special:MyLanguage/MediaWiki|MediaWiki software is developed collaboratively by hackers from all around the world. To help facilitate this process, standards of desirable practices have been established. While dev-policies>Special:MyLanguage/:Category:MediaWiki development policies|policies describe what developers must do, development guidelines typically describe what developers generally should do. There can be no deviations from policies dealing with such important topics as security>Special:MyLanguage/Security for developers|security for developers, even in man-ext>Special:MyLanguage/Manual:Extensions|MediaWiki extensions; but minor deviations from, say, cod-conv>Special:MyLanguage/Manual:Coding conventions|coding conventions are often allowable in extensions. Whether there is good reason for a given deviation that is worth the downsides of conformity to the established norms is a matter for judgment of developers and their code reviewers.