Lots of people will tell you that metadata is “data about data”. While this definition is commonly used, it isn’t very helpful. Instead, it can be more useful to think of metadata as after-data. This, after all, is one the original meanings of the word meta (μετά) in the greek language.
Metadata makes the world go round
Ask any data wonk and they’ll probably tell you that metadata makes the world go round . The internets is built on metadata. For example, the image in this blog post, you might search or browse to the data through it’s metadata not the data itself – the actual jpeg image file. The usual line is that the image metadata (title, author, date, tags etc) is data about data, e.g. it is data about the image.
Where you draw the line between data and metadata is a bit arbitrary. Is the author of the photograph data or metadata? It’s often difficult to tell because the defnition of metadata is so wishy-woshy, it’s almost meaningless. Some people call it metacrap, see picture on the right.
Afterdata: what comes afterwards
In Greek, μετά (meta) also means after. So metadata can be thought of as afterdata and this helps shed a little more light on what metadata actually is. Data is what you see or hear first. Metadata is everything that comes after. Simples!
It’s a small, possibly pedantic, distinction betweeen about-data and after-data but for my money, a potentially useful one. I wonder what the internets will make of it?
- Li Ding et al (2004). Swoogle: a search and metadata engine for the semantic web Proceedings of the thirteenth ACM international conference on Information and knowledge management, 652-659 DOI: 10.1145/1031171.1031289