This is way nerdy stuff - significant way nerdy stuff

A set of importer plug-ins that are used to populate the meta-data store and content index with information about the files on the file system.

A plug-in API allowing you to provide meta-data and content to be indexed for your application's custom file formats.

But more than a collection of individual technologies that work together, Spotlight gives you the ability to plug your application into the operating system and work with files in a totally new way. For example, if you were building an asset management application you could use Spotlight to find all of the files that match certain criteria rather than trying to slog through the file system yourself. Or, if your application specialized in supporting various kinds of workflows, you could use Spotlight to find all of the files that needed to be marked with a particular keyword. Once you get used to working with files in this new way, you'll never want to go back.

This article shows you how Spotlight works, how to programatically query the Spotlight Store, and how to create your own file format importers. As you can see, there is quite a bit of ground to cover. First, however, let's start out by defining what meta-data is.

What is Meta-data?

Meta-data is, succinctly stated, data about data. It provides a description about the data contained in a file such as (but not limited to) its height, width, size, creator, copyright holder, title, editor, created date, and last modification date. In practice, there is so much data that can be considered meta-data that these descriptions usually are generalized as a dictionary of descriptive attributes indexed by keys. You can think of it as the "what, when, and who" of a piece of data.

Some kinds of meta-data, such as file modification dates, ownership, and access permissions are kept external to the file by the file system and have been accessible via a variety of mechanisms. But the most interesting kinds of meta-data are found inside the file. For example, digital cameras embed all sorts of data, such as exposure information and whether a flash was used, into the image files that they produce. As well, files written by most applications, including Adobe Photoshop and Microsoft Word, contain quite a bit of meta-data.

Until now, this data has been buried in individual files, which has made it hard to work with and to search against. Spotlight gathers all of this information into the Spotlight Store allowing for quick, easy, and effective searches.