Online shopping and Web site tracking are other common uses of cookies. If you are forced to terminate your connection while shopping, the items will remain in your shopping cart until you reconnect to the site. Web developers and webmasters like cookies because cookies provide them with information. Cookies can tell the webmasters how many unique visits their sites have had, how often users return, where they go, and what they like. This information can help them generate more effective pages.
Advertising companies can use cookies to target ad banners.
One large advertising network, DoubleClick, has come under some criticism for trying to track customers by creating cookie-generated profiles. A cookie can only be read by the site domain that created it. Webmasters can't snoop through all your cookies and find out information about you. Viruses are carried by executable files. Since cookies are text only, which cannot contain executable files, they cannot carry viruses.