What is Metadata?

Jason C. Chavis

Metadata is essentially data about other data. Also known as metalanguage, metadata can be used in any sort of media to describe the contents of the information. The idea behind metalanguage is to provide documentation or information about a specific piece of data. When a document, image or other type of data is created, certain parameters need to be added behind the item as part of the whole file. These can include elements and attributes such as a name, size or type of file. It can also represent the location or ownership of the file amongst any other information that needs to be noted about the contents of the data.

Metadata may be found in books in regards to author and date of publication.
Metadata may be found in books in regards to author and date of publication.

Metadata is stored with a file at different levels of granularity. Granularity is essentially the detail of which this data is stored. Metadata can be formatted into a low granularity level where one line of data is established. It can also be more complex, with multiple lines of data stored in a detailed structure such as a database.

Digital cameras often record data about data.
Digital cameras often record data about data.

Uses of metadata include books, photographs, audio files, and web pages. Books would be filed with information regarding title, author, date of publication and possibly a unique identifier such as the International Standard Book Number (ISBN). Photographs usually include the time and date it was taken. Digital cameras often record data about data in a standardized format that is interchangeable with different brands. Likewise, digital audio files feature album names, song titles, year of publication and often genre. Web pages usually contain the most elaborate metalanguage. The Hypertext Markup Language (HTML) that makes up web pages includes everything from simple texts to dates and keywords. Metalanguage can include the page's header and are geotagged with coordinates for their location. Hypertext, which links web pages, also uses metalanguage.

Photographs commonly contain metadata in the form of time and date that a photo was taken.
Photographs commonly contain metadata in the form of time and date that a photo was taken.

The use of metalanguage speeds up the searching and locating of many resources. On the Internet, data about data aids in search queries through web browsers such as Google and Yahoo! It allows a user to save time when searching for information. The web browser automatically download metalanguage, making it part of the search process.

Oftentimes, metadata is formatted into a hierarchical system called “schema.” Certain data elements are used as descriptors for other data elements. This system can essentially continue forever into many levels. The format of the data about data is typically stored in a central location known as the metadata registry and helps organizations standardize their data. Most files, however, do not require such extensive information.

The language origin of metadata comes from the Greek prefix meta that describes being among something.

Web pages contain the most elaborate metalanguage.
Web pages contain the most elaborate metalanguage.

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Discussion Comments


How do you create a metadata file? Is it always done using html tags? What are its facets?


what is schema? like tags? what do they look like? and how do i add them in the metadata? or schemas make up the metadata? Please explain the schemas.


Is it OK to constantly delete: Users/myname/Library/caches/Metadata/Safari/Bookmarks and History?

Aren't they basically temporary internet files?

I noticed them one day while cleaning out: Users/myname/Library/Caches/com.apple.Safari/Webpage Previews.

I already try to private browse as much as I remember to, and while in Safari, I'll empty cache, but it doesn't seem to really clean temp internet files.

And they take a long time to delete! They must take a lot of space. Is there an easier way to automatically do this?


What meta data is stored for a MP3 music file, a J PEG image and a movie file?


@AstroTurf>> That’s quite a vague question. There is no single method for editing meta data in a file—it will vary immensely on the type of file. Asking ‘how can I edit metadata’ is like asking how do I cook dinner? It really depends on what you want to cook!

MP3 files have metadata which is editable through almost any media player software, including Windows Media Player and iTunes. For users that are needing a more powerful MP3 metadata editor, there are programs that specifically aim to process metatags on MP3s and other audio files.

HTML metadata is created by using HTML tags in a .html file. Renaming a file in any operating system is another way to edit metadata and I’m sure you’ve probably done this before if you've used a computer much!


How can I edit meta data on a file?

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