Does Mediawiki use jQuery?

MediaWiki, and thus Wikipedia, does use jQuery. See https://www.mediawiki.org/wiki/JQuery. But it isn't used for silly pointless animation and other gimmicks.

As other people said, Wikipedia does use jQuery. Quite a lot, in fact. The Wikimedia Foundation's developers also released several extensions for jQuery for internationalization, such as https://github.com/wikimedia/jquery.ime/, and contributed to the core jQuery and jQuery.ui code. A popup that displays information over links is already available as a gadget in the English Wikipedia - see https://en.wikipedia.org/wiki/Wikipedia:POPUPS. I tried it, and I'm happy that it's not enabled by default - it interferes with my browsing. People who like it can enable it manually. Of course, there are many other design improvements that can be done to Wikipedia. The Wikimedia Foundation tries to enable them based on testing with actual users and analyzing how they contribute to the user experience and to the site's mission - to gather human knowledge and make it accessible to all. Not every thing that looks like an improvement to you is actually useful to everybody. It's hard to find this balance, but it's possible. If you want to contribute to the design of the software behind Wikipedia, you are very welcome to see this page: https://www.mediawiki.org/wiki/Design.

I'll take a wild guess at what the reason for this is, although I'm only using Wikipedia as a source of finding things more than anything else. Here's a screenshot from just 5 minutes ago: What you are suggesting are general improvements to usability, which I think a lot of people would agree with, but you have to realize that these would come at a cost. Engineering time costs money. It might not look "fancy" but Wikipedia is a big, big website and it poses a lot of challenges such as scalability to a huge number of visitors with a low number of engineers. I think it's already hard for Wikipedia to keep up with serving billions of web page requests (http://stats.wikimedia.org/reportcard/), adding the hover-cards you suggested would add a lot to that, maybe on an order of magnitude more since every link hover would generate a new request (to make those hover-cards actually useful, you'll need to fetch quite a lot of data to keep them small but also relevant). It's really not what Wikipedia is about. Wikipedia wants to store all the knowledge we posses, make it searchable and available to everyone. The simple page format helps with keeping page size small and is an easy format for anyone willing to contribute to add too. I would say that a nicer design wouldn't really help Wikipedia with this goal at all. You can read more about the resources that the Wikipedia staff has and the state of things on the http://wikimediafoundation.org/wiki/Financial_reports#2012.E2.80.932013_fiscal_year page. There were several other suggestions on making Wikipedia better, similar to your question, the most notable one probably being http://www.wikipediaredefined.com/. Honestly, while I appreciate the fact that those mock-ups do look nicer, I don't really see any big improvements. Wikipedia is like the good old universal atlas, with the benefits that it contains way more knowledge, stays up to date, anyone can contribute, you don't have to carry it around and it's available freely as long as you have Internet access.   As a parallel, the http://archive.org has the same problems. You can read more about it at http://www.codinghorror.com/blog/2012/04/preserving-the-internet-and-everything-else.html.

Wikipedia DOES use jQuery. Open the browser console and type: > typeof(jQuery) "function"

There are a few tweaks that do what you're looking for. These can be turned on through the preferences pane when you are logged in. The most useful one in my experience is a tool called "Navigation Popups", which, well, pops up with a preview of a linked article one mouseover. More info on this gadget, as well as instructions on how to enable it, can be found at http://en.wikipedia.org/wiki/Wikipedia:Tools/Navigation_popups. This is just one of the many user-created scripts designed to alter and enhance the editing experience, but I think you will agree that changing the interface in this way for all readers would be a little extreme given the benefits are really designed to be enjoyed by editors.

Perhaps consider using another skin? There are a couple of popular Bootstrap styled skins available for Mediawiki which use jQuery and offer a range of effects including tooltips, just search for "Mediawiki Bootstrap".