Metadata is data about data.  Every time we use technology, be it a computer, a mobile phone, a camera or the internet, we leave a trail of information about what we do, how we do it, when and from where.   Metadata  that is recorded  in documents created on a computer generally include the name of the author, the time the document was created and when it was modified, a title of the document, keywords etc.; likewise cameras record information about the device, the time a picture is taken; and websites collect visitor IP addresses, web pages visited, user data and login details and so on.  

 The rationale for metadata use is to ensure information is findable, trustworthy, and understandable, and for that reason, there are established standards  for collecting and recording metadata. Many technologies are set up to automatically collect standard transactional and user data.  However, since leaked documents revealed that the US government was collecting such information and was using it, via the NSA's (National Security Agency)  secret surveillance program, to monitor the activities of individuals, it has become the subject of controversy, and seen as intrusive and an invasion of privacy. 

The UK Guardian has made available an interesting l "Guide to your metadata". Click here to access the guide. While the guide mentions that metadata collected from websites records  transactional information about visitors, and generally not personal or content-specific details, it illustrates how, in the case of the Petraeus scandal, even with the use of an anonymous email account, a cross-referencing of data from different sources allowed for identification of an individual. The Guardian guide points out that in some cases a person can limit the information that is collected, by turning off location services on cell phones, for instance,  however, often an individual may not have control over metadata that is collected.  At the very least, we can take the time to educate ourselves and be informed and vigilant.