DoubleClick.com is a media company that provides digital marketing and Internet advertising technology and services.When your Internet browser first visits a web page that uses DART technology for serving advertisements or recording web usage, your browser is assigned a test cookie to see whether your browser accepts cookies. This test cookie reads: test_cookie=CheckForPermission. If that cookie is accepted, when your browser next visits a DoubleClick-supported site, that test cookie is replaced by a cookie with a unique, anonymous number. This number is recorded in a small text file that is transmitted to your computer and stored in the cookie directory of your hard drive. Then, when you visit each web page on which the DART technology is used, DoubleClick.com servers can recognize your browser as a unique, anonymous user.
DART uses the DoubleClick.com cookie number to ensure that your browser does not see the same ad over and over again, to sequence ads in a series and to measure the number of unique visitors that have viewed a particular ad or visited a particular web page. Cookies, set or read with clear GIFs, are also used by advertisers for ad reporting functions such as to learn which of their ads are bringing users to their Web site to purchase or register. This can help advertisers tailor their ads and enhance their Web sites for their needs.