In computing, a theme is a preset package containing graphical appearance and functionality details. A theme usually comprises a set of shapes and colors for the graphical control elements, the window decoration and the window. Themes are used to customize the look and feel of a piece of computer software or of an operating system.
Also known as a skin (or visual style in Windows XP) [1] it is a custom graphical appearance preset package achieved by the use of a graphical user interface (GUI) that can be applied to specific computer software, operating system, and websites to suit the purpose, topic, or tastes of different users. As such, a skin can completely change the look and feel and navigation interface of a piece of application software or operating system.
Software that is capable of having a skin applied is referred to as being skinnable, and the process of writing or applying such a skin is known as skinning. Applying a skin changes a piece of software's look and feel—some skins merely make the program more aesthetically pleasing, but others can rearrange elements of the interface, potentially making the program easier to use.
Themes are often used to change the look and feel of a wide range of things at once, which makes them much less granular than allowing the user to set each option individually. For example, users might want the window-borders from a particular theme, but installing it would also alter the desktop background.
One method for dealing with this is to allow the user to select which parts of the theme they want to load; for example in Windows 98, users could load the background and screensaver from a theme, but leave the icons and sounds untouched.
Firefox and Google Chrome either support or supported a form of theme. Firefox (and its sibling Thunderbird) supports themes either through lightweight themes (formerly Personas). [3] Google Chrome version 3.0 or later allows themes to alter the appearance of the browser. [4] Internet Explorer 5 and its immediate successor allowed the background picture of their toolbars to be customized. [5]
The most popular skins are for instant messaging clients, media center, and media player software, such as Trillian and Winamp, due to the association with fun that such programs try to encourage.
Some platforms support changing the standard interface, including most using the X Window System. For those that do not, programs can add the functionality, like WindowBlinds for Microsoft Windows and ShapeShifter for macOS.
Many websites are skinnable, particularly those that provide social capabilities. Some sites provide skins that make primarily cosmetic changes, while some—such as H2G2—offer skins that make major changes to page layout. As with standalone software interfaces, this is facilitated by the underlying technology of the website—XML and XSLT, for instance, facilitate major changes of layout, while CSS can easily produce different visual styles.