Browser fingerprints

Definition
Browser fingerprints are

"the specific combination of characteristics &mdash; such as system fonts, software, and installed plugins &mdash; that are typically made available by a consumer's browser to any website visited. These characteristics can be used to uniquely identify computers, cell phones, or other devices. Browser fingerprinting does not rely on cookies."

External link

 * Erik Larkin, "Browser Fingerprinting Can ID You Without Cookies," PCWorld (Jan. 29, 2010).