Cookies are tiny bits of text stored on your PC by your web browser. They contain information that the web site needs to keep track of you from one request to the next. Once the web site has asked your browser to set the cookie, the next time your browser opens a new request your browser will send that cookie back to the web site.
There are two “categories” of cookies: either first-party or third-party cookies. First-party cookies are those cookies that belong to sites you actually visited in your browser, while third-party cookies, also known as tracking cookies, are generated from third-party advertising web sites.
The contents of cookies are set by the web site that you visited, so unless you’ve given your information to a web site, there’s no way that cookies are going to contain personal information.
Most cookies are as simple as a session token, but sometimes they contain your login credentials, usually encrypted or hashed in some format—but since cookies are only sent back to the same site that originated them, even if cookies contained personal information, it is not going to be shared with every site you visit.
Many people believe that cookies contain viruses or spyware. Cookies are nothing more than text files and could not be executed.
The majority of web sites require cookies to be enabled in order to create an account and keep yourself logged in, so if you disable cookies in your browser, a large portion of the web will not work. These cookies are considered first-party cookies, because they are set by the web site you purposely visited.
Still concerned about cookies for privacy reasons, you can set up your browser to only accept first-party cookies, so you’ll still be able to log in to all the web sites that you visit.