Spotlight is a technology for tracking files in terms of their features. These features of a file are called its metadata , and they include all sorts of information about the file: its name, its creation and modification date, its size, its contents, and so forth. Different kinds of files provide different kinds of metadata: for example, a word processing file has text contents, but an image file has a two-dimensional size, a resolution, and a color profile.
Spotlight knows how to extract metadata from many types of file; furthermore, any application can provide metadata information about whatever types of file are special to it, and Apple’s own applications, such as iCal, Mail, and Address Book, already do this. An unrestricted Spotlight search embraces all the kinds of metadata; a search on “rock” might find applications with “rock” in their name, word processing files with “rock” in their contents, iPhoto images with “rock” as a keyword, and MP3 music files with “rock” as their genre.
Note: As you experiment with Tiger, you’ll discover that Apple has modified some of its applications to allow you specify certain kinds of metadata. For example, user comments in a file’s Get Info window in the Finder are now called Spotlight Comments, and a TextEdit document now has Document Properties, such as an Author (choose File: Show Properties in TextEdit to see them). All of that is so this information can be found through Spotlight.
On the whole, you won’t be aware that Spotlight is present until you need it. After you first install Tiger, you may notice background disk activity, along with a subtle “throbbing” of the Spotlight menu icon, as Spotlight constructs an initial index of the metadata of all the files on your hard disk; this can take quite a long time (several hours). But after that, Spotlight becomes more or less invisible: the index is updated live each time you save or move a file (this happens so quickly that you probably won’t be aware of it). Thus, whenever you do a Spotlight search, it is usually rapid and completely up-to-date.
By now you’re probably chomping at the bit, eager to stop reading about Spotlight and to try it. Before we do that, here are some additional cool facts about Spotlight to get you drooling even more:
• It’s live: If the results of a Spotlight search are open, and if the situation on the hard disk changes—you download some files from the Internet, for example—the results of the search will change immediately to take those changes into account.
• It’s everywhere: When you perform a local (non-Internet) search in any Apple application, you’re probably using Spotlight. The search field in the System Preferences window, the search field in a Finder window, the search field in the Mail window—they’re all Spotlight. As Tiger matures, third-party developers will add Spotlight searching to their applications as well.
• It’s persistent: A Spotlight search can be saved, and various Apple applications provide a way to do this. The Finder gives you Smart Folders (which I talk about more in a moment); Mail gives you Smart Mailboxes; Address Book gives you Smart Groups. Because a Spotlight search is live, any time you open a Smart Folder or a Smart Mailbox, it updates immediately.