The reason it can do this so quickly, is because Spotlight indexes all the files on your computer, transparently in the background, so you don't experience any slowing of your system. Every time you add, delete or edit a file, Spotlight automatically updates the indexes.

When you use Spotlight, you're not only searching for filenames, but also accessing all the associated data that is part of a file; not only creation and modification dates, file types, etc., but also the "what, when and who" of every piece of information saved on your Mac. This kind of information is called metadata, and most documents, including Microsoft Word, Photoshop, emails and most JPG's, contain this metadata information.

And because Spotlight indexes content as well, your search results include what appears inside a file or document, not just its title.

With Spotlight, you find what you want with uncanny accuracy, even when you don't know many details. For example, if you know roughly when you saved or received something, you can type in relative time periods like Date:Yesterday to find it. If you're not sure of an item's file format, use kind to find types of files including Kind:Movie, Kind:Image or Kind:Document. Spotlight displays a neatly sorted result list that you can browse to find what you want.

Thanks to the speed and flexibility of Spotlight, you will discover countless new ways to organize your files. Take the results of a search and save it as a Smart Folder that automatically updates as you add or remove documents from your Mac. Smart Folders contain files grouped together based on search criteria instead of physical location, so the same file can appear in multiple Smart Folders without moving from its original saved location on your system. No need to duplicate, shift or update files: Spotlight Smart Folders keep everything organized for you.

Thanks to Spotlight and its range of supported formats, you can find anything on your Mac, from text hidden within a PDF document to an image shot with a particular camera. By putting this phenomenal search technology at your fingertips, Spotlight and Mac OS X will change how you find, organize and value the information saved on your computer.