Spotlight
Spotlight is the system-wide desktop search feature built into Apple's OS X operating system since version 10.4 (Tiger). Backed by an index of all items and files on the system, it's designed to allow the user to quickly locate a wide variety of items on the computer, including documents, pictures, music, applications, and System Preferences. In addition, specific words in documents and in web pages in a web browser's history or bookmarks can be searched. It also allows the user to narrow down searches with file attributes (e.g. creation dates, modification dates, sizes, types) and, as of OS X 10.9, tags. Pre-installed plugins for the New Oxford American Dictionary and Calculator applications also included in OS X allow Spotlight to define words and evaluate mathematical expressions. Adapted from Wikipedia: http://en.wikipedia.org/wiki/Spotlight_ (software)
