Remarketing is a way for you to reach people who have already visited your website. When someone visits a website, they receive a cookie from that site. The cookie stores information and can be read by the web server when the visitor comes back to that site. A cookie often includes the name of the domain and a unique ID number that identifies each user.
Remarketing allows you to take advantage of this unique ID in order to serve relevant ads to visitors who have previously been on your website, even if they are returning many months later.
Using remarketing helps you to increase brand awareness, drive sales and increase conversions by showing ads to people who have already shown interest in your brand or website.