The sites you visit have access to any information pertaining to your browsing of that site. For instance, online retailers can tell whether you got to their site by clicking on a link from search engine results or if you found them from another website, perhaps an affiliate site running one of the store’s ads. Once you are on a site, it can see which pages you visit and how long you stay on each page. This helps online retailers determine which products you are most interested in, so they can tailor their marketing efforts toward products you are more likely to purchase. Non-retailers use similar information to track the popularity of posts, determine interest trends, or to tailor marketing based on the type of information you’re looking at. If you create a profile with a site, they can use also any personal information you provide to improve content or product inventory or tailor ads to your specific demographic.