Desktop search (sometimes called integrated search) is the ability to simultaneously search hard drives and removable storage on the user's computer.
Desktop search programs create an index of files stored on the computer, which enables fast and fairly comprehensive searches. The user can search local hard drives, Web sites, e-mail, and other sources without having to minimize the current document or open a browser, e-mail client, or other application.Content Continues Below
Here's how the Google desktop search works: After the search application is installed, the program creates an index of user selected hard drive content. In addition to text documents, spreadsheets, presentations, and e-mail, there's an option to include instant message logs and Web browsing history, which the application will record and store. The search tool is accessible from an icon in the system tray. Clicking the item brings up a page that looks much like the familiar Google search page, but you can choose to "Search Desktop" or "Search the Web." Integrated search results are available as an option. When the user types a search term into the text box, the program coordinates searches of the user-selected sources, and displays the results, organized according to type (for example, "11 emails - 1 file - 5 chats - 3 web history").