Spotlight is a system-wide desktop search feature of Apple's macOS and iOS operating systems. Spotlight is a selection-based search system, which creates an index of all items and files on the system. It is designed to allow the user to quickly locate a wide variety of items on the computer, including documents, pictures, music, applications, and System Settings. 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 creation dates, modification dates, sizes, types and other attributes. Spotlight also offers quick access to definitions from the built-in New Oxford American Dictionary and to calculator functionality. There are also command-line tools to perform functions such as Spotlight searches. Spotlight was first announced at the June 2004 Worldwide Developers Conference, and then released with Mac OS X Tiger in April 2005. A similar feature for iPhone OS 3 with the same name was announced on March 17, 2009. macOS Indices of filesystem metadata are maintained by the Metadata Server (which appears in the system as the mds daemon, or mdworker). The Metadata Server is started by launchd when macOS (formerly Mac OS X, then OS X) boots and is activated by client requests or changes to the filesystems that it monitors. It is fed information about the files on a computer's hard disks by the mdimport daemon; it does not index removable read-only media such as CDs or DVDs, but it will index removable, writable external media connected via USB, FireWire, or Thunderbolt, and Secure Digital cards. Aside from basic information about each file like its name, size and timestamps, the mdimport daemon can also index the content of some files, when it has an Importer plug-in that tells it how the file content is formatted. Spotlight comes with importers for certain types of files, such as Microsoft Word, MP3, and PDF documents. Apple publishes APIs that allow developers to write Spotlight Importer plug-ins for their own file formats. The first time that a user logs onto the operating system, Spotlight builds indexes of metadata about the files on the computer's hard disks. It also builds indexes of files on devices such as external hard drives that are connected to the system. This initial indexing may take some time, but after this the indexes are updated continuously in the background as files