See also: Web browser
A text file that web sites can leave on your hard drive while using web browser software. Cookies can cause privacy and security concerns because they can allow tracking and hurt anonymity with their use and misuse. Different web browsers have different settings to allow or disallow cookies.
Positively, a cookie can save information about you so that you do not have to log-in to a Web site over and over, saving you time. Negatively, it can contain your credit card information, which may or may not be stored securely, making you prone to identity theft.