Metadata provides information about your files.
You might hear the prefix meta applied to other things. It really just adds a higher level to whatever it describes. So metadata is information about your data. It’s data that describes your data in the files.
Metadata includes things such as when a file was created, when was it last changed, who is the author, etc. And depending on the type of file, there could be more. A picture or image file could have information about where and when the picture was taken, what camera was used, the dimensions, etc.
You can use this information to gain more insight into your files. And applications can use it to give you more ways to organize your files. So instead of just looking at a list of files and folders sorted by name, you can view them sorted by their original author name.
The extra information is also called either properties or attributes. Sometimes you might also hear the term extended attributes. This metadata needs space somewhere. I mean, remembering if a file should be read-only needs at least a single bit to be set to either 0 or 1 and that bit needs to be saved somewhere. The same thing with the name of the author and other properties.
Listen to the full episode for more information about where a filesystem might store these properties. This includes a description of a forking filesystem and alternate data streams.