为善用我们有限的资源，由2013年4月15日至24日期间，除Vector legacy (2010)、MonoBook、Modern及Cologne Blue以外的皮肤都将永久从MediaWiki及所有的维基媒体项目中移除。如果您的用户设置使用了过时的皮肤，届时将会自动的将其设置为默认皮肤Vector。
About 0.53% of active Wikimedia users, and about 0.39% of active users with more than 1,000 edits. It also affects 0.31% of Wikimedia users who are no longer active (no edits or log-ins in the last six months). A full statistical break-down is available.
What do I need to do?
If you used Monobook, Modern, Cologne Blue, or Vector (e.g. if you've never changed this preference), this will not affect you at all, and you don't need to do anything. If you currently use an old skin and you're happy to use the default skin on each wiki (Vector), you don't need to do anything.
Otherwise, you can go to Special:Preferences in your Personal tools at the top of any page, click on the second tab ("Appearance"), and select one of "Vector", "Monobook", "Modern" or "Cologne Blue", then press "Save" at the bottom of the page. If you're not sure which skin you use, you can follow the same advice to find out.
Why are you doing this?
The problem is that because we have so many old skins, building in support for them is expensive in terms of developer time (and so in terms of donor funds). The more time we have to spend making something work with nine or ten different skins, the less we have to build new features or maintain our existing software. It also limits the things we can actually build, since some highly useful features might simply not work with skins from 2001 or 2002. The end result is we have to choose between producing limited software very slowly, breaking the site for a chunk of our community, or switching skins off; we've chosen the third.
Why are you keeping these four skins?
The skins we will currently keep available – Vector, Monobook, Modern and Cologne Blue – were selected because they currently work with the features we provide and/or have active maintainers. Vector is the official skin that we provide and keep up-to-date for all new developments and to fix bugs. The other three (Monobook, Modern and Cologne Blue) are supported primarily by volunteer developers who donate their time to keeping these skins available. We at the Wikimedia Foundation will try to ensure "graceful degradation" for these older three skins, so that newer functionality will work to some extent. Over time, however, if they break we may need to disable those too.
Aren't the old skins better for people on slow connections/computers?
On the other hand, Vector and Monobook use several background images (unlike, for example, the Classic/Standard skin), which might slightly increase CPU load. Modern and Cologne Blue are free of this issue.
Customized JS/CSS scripts, written to mimic the old skins, will also cause additional download time.
If you need help, please post clear, actionable, and discrete requests to Tech describing which specific feature from an older skin you would like to see in a newer skin. For example, "I was using the Classic skin and I'd like to use Monobook now. How do I adjust the font to be serif instead of sans-serif?"