Curtilage - basically defined as "a piece of ground (as a yard or courtyard) within the fence surrounding the house" [Webster's New Collegiate Dictionary]. But its protection as constitutionalized in the Third and Fourth Amendments is "essentially a protection of families and personal privacy in an area intimately linked to the home, both physically and psychologically, where privacy expectations are most heightened." [California v. Ciraolo, 476 U.S. 207, 212-13 (1986), cited by Kang, J. (1998) in his article, Information Privacy in Cyberspace Transactions, note 24, infra].

Spatial Privacy - the first cluster of privacy defined by Kang, J. (1998) - "concerns physical space, in particular, the extent to which an individual's territorial solitude is shielded from invasion by unwanted objects or signals. [It] is the sort invoked by sociologist who discuss private versus public territories and territorial overcrowding. It is this sense of privacy that informs the Fourth Amendment search-and-seizure concept of curtilage. This is also the sense of privacy employed when one complains about a car alarm or a telemarketing call disturbing one's privacy."

Decisional Privacy - the second cluster of privacy defined by Kang, J. (1998) - "views privacy as principally concerned with choice, an individual's ability to make certain significant decisions without interference. [It] is the sort discussed in famously in Roe v. Wade. This conception of privacy is less concerned with the maintenance of spatial boundaries and more concerned with a person's freedom to make self-defining choices without state interference." Of the three privacy clusters that Kang defined, he writes that decisional privacy "has incited the most contentious constitutional and political battles."

Informational Privacy - the third cluster of privacy defined by Kang, J. (1998) - "concerns the flow of personal information. More precisely, [it] concerns an individual's control over the processing - i.e., the acquisition, disclosure, and use - of personal information." Kang qualified his definition of informational privacy by writing that "in this cluster, the paradigmatic privacy violation does not occur, for instance, when the state places an undue burden on some significant decision. Rather, this strand of privacy is invaded when, for example, someone obtains sensitive medical data by rifling through confidential files without permission."

Inviolate personality - a term used by Warren and Brandeis (1890) in their paper (L. Brandeis & S. Warren. "The Right of Privacy." Harvard Law Review. 4(1890): 193-220.) that has become the seminal paper on the right to privacy. In that paper, Warren and Brandeis wrote, "The principle which protects personal writings and all other personal productions, not against theft and physical appropriation, but against publication in any form, is in reality not the principle of private property, but that of an inviolate personality." Further, in another section of the paper, they wrote, "...the more general right to the immunity of the person, --the right to one's personality."

Expectation of privacy - an expectation of privacy is normatively defined and sanctioned by society and measured against what a reasonable person could reasonably expect in any given situation. A reasonable person does not have a reasonable expectation of privacy in naturally-occuring private situations as when he/she is walking in quiet contemplation in a secluded but publicly-owned woods and there comes this group of rowdy teenagers running wildly through the woods and disturbing his/her peace. But a person can have a reasonable expectation of privacy when his peace and quiet is disturbed by the constant ringing of the phone caused by calls from telemarketers. The line between naturally-occuring and normatively-occuring private situations is not that easy to draw.

Confidentiality of Information - is defined in Kang, J. (1998), note 50 infra, as "a measure of the degree and terms of disclosure." Kang differentiates information privacy and confidentiality in two ways: (a) "privacy concerns itself only with personal information, whereas confidentiality is relevant to all types of sensitive or valuable information." (b) "information privacy is not only concerned with the disclosure of personal information, but also with its acquisition and use. Even if personal information is maintained confidentially, it still can be used inappropriately."

Security - is defined in Kang, J. (1998), note 60 infra, as measuring "the degree of confidentiality, integrity, reliability, and availability of information and related systems." Kang notes that, like confidentiality, security is also a term consistently confused with privacy. Information privacy concers only information that is identifiable to a person whereas security is relevant to all types of information. Kang suggests, for the policymaker's lexicon, that "privacy should appear prior to security because privacy answers "what to do," whereas security answers "how to do it.""

Note: If the link to Kang's article has changed (as happened before and might happen again), please go to his website and follow the links to his publications. The URL to his website is http://www.law.ucla.edu/kang/index.html. Better to bookmark this URL since you also get an update on his studies on cyberprivacy and related topics.