- [Instructor] Metadata is data about data,
or in other words,
it's any information that can be derived from
or attributed to a particular piece of data.
Often this information provides additional detail
that isn't included in an actual piece of data.
It's information that describes the contents,
provides context, or records associated information
without altering the original data.
While we'll focus on file
and file system metadata in this course,
metadata isn't strictly a computer related concept.
For example, if we were to call a friend on the phone
and have a conversation with them,
the actual content of our conversation
would be what we'd call the data.
But anything else about that call such as
the date and time it took place,
a summary of the topics covered,
or how long we spoke for,
is metadata in relation to the conversation.
These are things we could write down to describe
our conversation should we need to recall it later.
To move back to the realm of files,
imagine that we had recorded our conversation
to an audio file.
This file would likely have metadata such as duration,
possibly tags we add with a participant's names
and other tags with conversation topics.
As a file, it will have a creation date,
though that might start out as the date when the file
was created, not when the conversation actually took place.
That file will have a size in bites representing
how much disc space it takes up,
and it will have to some degree access permissions,
indications defining which users of a system
can do what actions with it,
depending on how it was created.
Many other kinds of files have various
metadata associated with them too.
Images, for example,
often contain information about
the camera used to take a photo,
the focal length and lens used,
and sometimes geolocation information
and the photographer's name.
Video and audio files have a duration
and sometimes will include a thumbnail or album cover.
Documents will often have authorship information,
revision history, a page count, sometimes a summary,
and more stored in their metadata.
And all of these files, no matter what kind they are,
have a size and a name, various date information,
and may have other kinds of attributes as well,
like tags or color highlights or access permissions.
While pretty much any data we can tag onto a file
or associate with it is metadata,
there are two primary ways of storing metadata
that relate to files.
One type of metadata is stored inside the file it describes.
It's embedded within the file.
Examples of embedded metadata are EXIF tags for photos,
listing a camera model or lens focal distance,
or an audio files ID3 tag listing
a music artist, a track name, and so on.
And some file metadata like the file's
name and date information,
it's access permissions and extended attributes
are stored outside the file it describes,
in the file system, not within
the actual data of the file.
We'll explore both of these types of metadata
throughout the rest of the course.
All this metadata can be gathered, stored, and indexed,
making it easier to find files based on their name
or some other aspect.
With the basics behind us,
let's move on to exploring metadata
and its security implications in more depth.