First concept Cookies
A cookie is a file that is downloaded to the PC / Smartphone / Tablet user to access certain web pages to store and retrieve information about the navigation is done from that computer.
Cookies specifications suggest that browsers must support a minimum number of cookies or a minimum amount of memory to store them. Specifically, a browser is expected to be able to store at least 300 cookies 4 kilobytes each, and at least 20 cookies per domain or server.
The server sets the cookie can specify a deletion date, in which case the cookie will be deleted on that date. A shopping site might want to help potential customers remembering the things he had in his shopping cart, even if you close the browser without making the purchase and return later to avoid having to find new products. In that case, the server would create a cookie deletion date according to the desire of the designer of the website. If a deletion date is not set, the cookie is deleted when the user closes their browser. Therefore, define a deletion date is a way to make the cookie survive across sessions. For this reason, dated erase cookies are called persistent. For more information on cookies, we suggest that you can access the following link: http://www.iabspain.net/privacidadeninternet/usuario
Second Cookies that used website