A stand-alone application or function built into the operating system that is used to find data in a user's computer, including the built-in drives and any external drives that may be connected. Desktop search is standard in Windows and Mac, and users can search file and folder names, the metadata (title, author, etc.) within multimedia files and the content of popular file formats such as word processing documents, spreadsheets, email messages and contact lists. The Web can also be added to the search.
Indexes are the Key to Quick Searches
In order to search the computer quickly, desktop search programs create and maintain indexes of the computer's files. It can take several minutes to index all the files the first time; however, subsequent file additions and deletions are indexed in real time.
Enterprise search extends desktop search across the local network, allowing authorized users to search for data in servers and other users' computers. See Google Desktop
and Win Desktop search
The Mac's Desktop Search
Spotlight is the desktop search in macOS. Spotlight searches for data in all these categories of data within the computer unless the user unchecks a selection.