As PC hard drives get bigger and new information sources become available, users will have much more data of different types, including multimedia, on their computers. This makes it increasingly difficult to find documents, e-mail messages, spreadsheets, audio clips, and other files. Current desktop-based search capabilities, such as those in Windows, are inadequate to meet this challenge. Desktop search features built into current operating systems, e-mail programs, and other applications have far fewer capabilities than Web search engines. They generally offer only simple keyword searches of a set of files, usually of a single file type. However, desktop search engines face the additional challenge of recognizing which of the many file types it is dealing with. The engines also must derive whatever metadata authors have chosen to include in e-mail notes, database files, and other document types. Desktop engines must be efficient and avoid imposing a substantial processing or memory load on the computer. Integrating desktop and Web search capabilities into the same application presents security and privacy challenges.