A German website has managed to track a German politicians movements over half a year using metadata. the degree of how closely they are able to track the politician and how often he gives away metadata.
Metadata is the surface content of the piece of information. in the case of a phone call, as is in the article, it would include information such as:
Who called who,
Date and time
Location call was placed
When you collect a lot of this metadata it adds up and begins to paint a picture of a person’s life
This article helps to show the value of metadata and what it can be used for.
Watch the politicians movements here