The marketer includes a pixel within their webpage which sets a cookie in the user's browser.
Site retargeting is now commonly considered a "standard practice" among digital marketers.
[2] The ability to "retarget", or sell ads on different websites to visitors of certain webpages, lays at the heart of most social networks business models.
LinkedIn,[3] Facebook,[4] Twitter,[5] Pinterest[6] & more all allow and have detailed guides on how to run retargeting ads on their platforms.
Google's business model is also built on retargeting - both in their search engine and in their display advertising network.