By Dan Thomas, map by John Burn-Murdoch

The animated map below shows a year’s worth of my mobile phone data obtained from my mobile operator, Three.

Every point that appears on the map is a phone call I made or text message I sent, with the location derived from the handset’s distance from the nearest antenna masts.

This news story has more detail on the reasons companies hold this data, the implications for your privacy and other cases where individuals have used data request laws to shed light on just how much personal information organisations hold.

All companies in the EU will give users data held on them on request, although some are better at responding than others. The easiest way to obtain data from communications groups is the way I did, through a subject access request. These can be made through a form that most companies should have on their websites or be able to provide.

Making a subject access request is normally a simple process where you can list what information you require. There is also normally a processing fee involved, followed by a wait of several weeks.

There is wide difference in availability of data held by internet groups, with companies such as Google making it easy to search through the information ranging from location to preferences through various parts of its websites (such as the location history section of its mapping application, or its advertising preferences page).

Websites and applications such as Facebook provide details through account settings, while companies such as Microsoft can be contacted directly with requests for data.

However, drilling into data held by other websites and applications on your phone can become more difficult, in particular if they are often based in other countries.

While occasionally painfully slow and laborious, an occasional data audit, updating preferences and assessing the extent of third party access to data should be a new year’s resolution for most people.