Data Controller
A person who determines the purposes for which and the manner in which personal data are to be processed. To qualify, the person must have some sort of intellectual input. For example, they may have passed an opinion about the person or decided to record some details about the person or his views. Data controllers are usually companies or a government body.
Data controllers often hold the belief that because they are in possession of personal data, the data belong to them. They do not. They may own the medium on which the personal data are recorded – the hard drive for example - but not the personal data on the hard drive. If the data are personal, then they belong to the data subject. That does not mean that the data controller cannot process those data – store them, use them and so on – but they are and remain, the personal data of the data subject. Personal data can have more than one controller. You are not a data controller if you ‘process’ data for ordinary household reasons.