One of the most profitable, highest-converting campaigns you can make in your Adwords account is a remarketing campaign.
The concept of remarketing campaigns is simple: everyone who visits your website and doesn’t convert is added to what’s called a “remarketing audience.” As they navigate around the web on other sites, they will continue to see ads via the Google Display Network, which displays the content or product they viewed on your website. Ideally, then, these users click on the display ad and visit your website again and make a purchase or complete a conversion goal.

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