A synonym for a Theme.
A Skin or evoSkin in b2evolution is what gives its particular look and feel to the Front Office (the part that is visible to the public) of Blog or to a Collection of any kind.
Some Skins specialize in displaying a Photoblog, a Forum or an Online Manual whereas many Skins are more generic and may work for a wide range of Blogs or Collection types.
There are other ways to customize the look & feel, but evoSkins are the preferred way of giving a specific look and feel to your blog. See the chapter Customizing the Look & Feel for more information.