Another type of retargeting that you can do aside from site retargeting (meaning putting a pixel from your site on their browser), using the same pixel idea, is to use search marketing by using Google Ads and Google Search targeting.
The way it works is that someone who has been on your site before goes to Google to search for more information about the topic that led them to your site the first time. Now, when they go to the search and type in the right search terms that you’ve studied and bid on, they’ll again be delivered your results on search.
This will bring them back to your site because they’ll recognize it and Google is recommending it to them. When they come back, they’ll have about a 40 percent chance (according to Moz.com) to make a purchase or convert to your email list after reclicking and re-engaging with you depending on your CTA. If you want to try this, go to your Google AdSense account and give it a try.