What is a cookie?
A cookie is a short text file sent to your browser from the web server or web servers that host the files of the website you are viewing. You may encounter two types of cookies: session cookies and persistent cookies. Session cookies are only active as long as you’re using your browser. Once you close your browser, the cookie is deleted. Persistent cookies remain on your hard drive until they reach their expiry date or you delete them.
Cookies, whether session or persistent, can also be described as first-party or third-party cookies. A web page’s content may come from more than one server. Third-party cookies are related to content on a web page that does not come from the page’s primary server. These third-party cookies are sometimes used to compile usage statistics on behalf of the site owner or, on commercial web sites, they may be associated with advertising and are used to track the effectiveness of the ad. To protect your privacy, your browser only permits a web server to access the cookies already sent to you from its domain, not the cookies sent to you by web servers from other domains.