On Wikipedia and other sites running on MediaWiki, Special:Random can be used to access a random article in the main namespace; this feature is useful as a tool to generate a random article. Depending on your browser, it's also possible to load a random page using a keyboard shortcut (in Firefox, Edge, and Chrome Alt-Shift+X).
To create a link to a random page in a different namespace, use [[Special:Random/Namespace]]. For example, Special:Random/Talk will take you to a random article's talk page.
If you are wondering if the "random article" feature is really random, read the answer here.