Desktop search is the name for the field of search tools which search the contents of a user's own computer files, rather than searching the Internet. These tools are designed to find information on the user's PC, including web browser histories, e-mail archives, text documents, sound files, images and video.

One of the main advantages of desktop search programs is that search results arrive in a few seconds; Windows search companion can be some help, but it searches through Windows files and folders only, not e-mail or contact databases, and unless you enable the Indexing Service (in Windows 2000 or XP), the Windows search tool is extremely slow. Windows Vista enables the indexing service by default.

A variety of desktop search programs are now available; see this list for examples.

Desktop search is emerging as a concern for large firms for two main reasons: untapped productivity and security. A commonly cited statistic states that 80% of a company's data is locked up inside unstructured data — the information stored on an end user's PC, the files and directories they've created on a network, documents stored in repositories such as corporate intranets and a multitude of other locations. Moreover, many companies have structured or unstructured information stored in older file formats to which they don't have ready access.

Technologies

Desktop search engines build and maintain an index database to achieve reasonable performance when searching several gigabytes of data. Indexing usually takes place when the computer is idle and most search applications can be set to suspend it if a portable computer is running on batteries, in order to save power. When indexing the files, desktop search tools collect three types of information about files:

• file and directory names
• metadata, such as titles, authors, comments in file types such as MP3, PDF and JPEG
• content of supported documents.

To search within documents, the tools need to be able to parse many different types of documents. This is achieved by using filters that interpret selected file formats. For example, a Microsoft Office Filter might be used to search inside Microsoft Office documents.

Long-term goals for desktop search include the ability to search the contents of image files, sound files and video by context .

The sector attracted considerable attention from the struggle between Microsoft and Google. According to market analysts, both companies are attempting to leverage their monopolies (of web browsers and search engines, respectively) to strengthen their dominance. Due to Google's complaint that users of Windows Vista can not choose any competitor's desktop search program over the built-in one, an agreement was reached between US Justice Department and Microsoft that Windows Vista Service Pack 1 will enable users to choose between the built-in and other desktop search programs, and select which one is to be the default.