Data privacy is the relationship between collection and dissemination of data, technology, the public expectation of privacy, and the legal issues surrounding them.

Privacy concerns exist wherever personally identifiable information is collected and stored - in digital form or otherwise. Improper or non-existent disclosure control can be the root cause for privacy issues. Data privacy issues can arise in response to information from a wide range of sources, such as:

• Healthcare records
• Criminal justice investigations and proceedings
• Financial institutions and transactions
• Biological traits, such as genetic material
• Residence and geographic records
• Ethnicity

The challenge in data privacy is to share data while protecting personally identifiable information. The fields of data security and information security design and utilize software, hardware and human resources to address this issue.

Information types

Various types of personal information often come under privacy concerns.

Lifestyle

For various reasons, individuals may not wish personal information such as their religion, sexual orientation, political affiliations, or personal activities to be revealed. This may be to avoid discrimination personal embarrassment, or damage to one's professional reputation.

Financial

Information about a person's financial transactions, including the amount of assets, positions held in stocks or funds, outstanding debts, and purchases can be sensitive. If criminals gain access to information such as a person's accounts or credit card numbers, that person could become the victim of fraud or identity theft. Information about a person's purchases can reveal a great deal about that person's history, such as places he/she has visited, whom he/she has contacted with, products he/she has used, his/her activities and habits, or medications he/she has used. In some cases corporations might wish to use this information to target individuals with marketing customized towards those individual's personal preferences, something which that person may or may not approve of.

Internet

The ability to control what information one reveals about oneself over the Internet, and who can access that information, has become growing concerns. These concerns include whether email can be stored or read by third parties without consent, or whether third parties can track the web sites someone has visited. Another concern is whether web sites which are visited collect, store, and possibly share personally identifiable information about users.

The advent of various search engines and the use of data mining created a capability for data about individuals to be collected and combined from a wide variety of sources very easily.

Medical

A person may not wish for their medical records to be revealed to others. This may be because they have concern that it might affect their insurance coverages or employment. Or it may be because they would not wish for others to know about medical or psychological conditions or treatments which would be embarrassing. Revealing medical data could also reveal other details about one's personal life (such as about one's sexual activity for example).