Privacy is the ability of an individual or group to seclude themselves, or information about themselves, and thereby express themselves selectively. The boundaries and content of what is considered private differ among cultures and individuals, but share common themes. When something is private to a person, it usually means that something is inherently special or sensitive to them. The domain of privacy partially overlaps security (confidentiality), which can include the concepts of appropriate use, as well as protection of information. Privacy may also take the form of bodily integrity.
The right not to be subjected to unsanctioned invasion of privacy by the government, corporations or individuals is part of many countries' privacy laws, and in some cases, constitutions. Almost all countries have laws which in some way limit privacy. An example of this would be law concerning taxation, which normally require the sharing of information about personal income or earnings. In some countries individual privacy may conflict with freedom of speech laws and some laws may require public disclosure of information which would be considered private in other countries and cultures.
Privacy may be voluntarily sacrificed, normally in exchange for perceived benefits and very often with specific dangers and losses, although this is a very strategic view of human relationships. Research shows that people are more willing to voluntarily sacrifice privacy if the data gatherer is seen to be transparent as to what information is gathered and how it is used. In the business world, a person may volunteer personal details (often for advertising purposes) in order to gamble on winning a prize. A person may also disclose personal information as part of being an executive for a publicly traded company in the USA pursuant to federal securities law. Personal information which is voluntarily shared but subsequently stolen or misused can lead to identity theft.
The concept of universal individual privacy is a modern construct primarily associated with Western culture, British and North American in particular, and remained virtually unknown in some cultures until recent times. According to some researchers, this concept sets Anglo-American culture apart even from Western European cultures such as French or Italian. Most cultures, however, recognize the ability of individuals to withhold certain parts of their personal information from wider society—closing the door to one's home, for example.
The distinction or overlap between secrecy and privacy is ontologically subtle, which is why the word "privacy" is an example of an untranslatable lexeme, and many languages do not have a specific word for "privacy". Such languages either use a complex description to translate the term (such as Russian combining the meaning of уединение—solitude, секретность—secrecy, and частная жизнь—private life) or borrow from English "privacy" (as Indonesian Privasi or Italian la privacy). The distinction hinges on the discreteness of interests of parties (persons or groups), which can have emic variation depending on cultural mores of individualism, collectivism, and the negotiation between individual and group rights. The difference is sometimes expressed humorously as "when I withhold information, it is privacy; when you withhold information, it is secrecy."
On December 15, 1890, Samuel Warren and Louis Brandeis published the article of the law called "The right to privacy", considered one of the most influential papers in the history of American law.