Fingerprinting is a practice in which websites identify a particular browser (and by extension, a particular user) by collecting and combining distinguishing features of the browser and underlying operating system. Elements of a fingerprint might include, for example:
- the browser version
- the timezone and preferred language
- the set of video or audio codecs that are available on the system
- the fonts installed on the system
- the state of the browser's settings
- the computer's display size and resolution
Web standards are designed in such a way as to minimize the ability of a website to collect identifying information, and browsers typically add their own protections as well.
- Cover Your Tracks: a tool to show the data a website can use to fingerprint your browser.
- Mitigating Browser Fingerprinting in Web Specifications: best practices for specification authors to prevent fingerprinting.