It is encouraged that users should source articles with relevant links as appropriate references. Strongly encouraged are primary sources; these are links from websites where content originates from (for example, a video game developer's website). To be avoided where possible are secondary sources; these are links from websites that aggregate news from elsewhere, and may introduce bias and/or inaccuracies.
For links that involve highlighting information that may later be removed (such as Reddit posts, Twitter tweets, etc), an archive link is advised. An archive link preserves the page layout for the time it was taken, like a "snapshot" of how the site looked. This is extremely useful to hold both developers, publishers, and journalists to account; if one can easily delete information, it is easy to publish falsehoods and untruths. The most common archival site that is used is Archive.is, as the site does not de-list archived pages on request.
While it is an accepted fact that Wikipedia is a good resource for MediaWiki-related templates and code, the content on the site is becoming highly questionable, especially given the collusion between high-ranking members on certain topics. If it can be avoided, Wikipedia should not be used as a source if there is an acceptable alternative. Previous articles imported from Wikipedia are still permitted to link back to the parent article.