Cookie: Not to be confused with baked goods, cookies are files sent by a website and saved by a user's web browser. These files store various types of information about a user's activities on a particular website. They are sometimes referred to as HTTP cookies, web cookies, or browser cookies.
The information stored in a cookie can include website preferences, stored log-in information, purchases, clicked advertisements, and referring links (e.g. what other website a user arrived from). These cookies are stored within a temp or temporary internet file folder on a user's computer.
Cookies vary in terms of security; some are secure (only available through HTTPS) and others, such as third party tracking cookies, can be used for more malicious purposes. Tracking cookies are usually, but not always, deployed through advertisements. They may appear in a temporary file folder with a name like "ad.exampletracking.com." As of 2014, the average website sets 10 cookies readable by third-party domains (i.e. passing information on to as many as ten different third parties). The highest number of cookies found, according to research, was 800 on a single website.
Many internet security experts recommend that users delete their cookies from their browsers in order to prevent confidential information from being stolen. Certain virus, adware, and malware detectors will sometimes clear cookies that may be malicious.