Question

Q: I want to know :

1. Can the .skin files replace the
   CSS files?

2. What are the advantages of
   .skin files?

3. Can .skin files offer more
   than CSS files?

   and

4. When to use skin files in my web
   application?

Answer 1

Asp.net skins are one part of asp.net Themes. From the MSDN docs:

Themes are made up of a set of
elements: skins, cascading style
sheets (CSS), images, and other
resources. At a minimum, a theme will
contain skins. Themes are defined in
special directories in your Web site
or on your Web server.

Skins are used to define default markup for asp.net server controls:

<asp:button runat="server" BackColor="lightblue" ForeColor="black" />

whereas CSS is used to style your native HTML elements (of course asp.net server controls render as native elements so CSS can also be used to style these