A first-party cookie is a code that gets generated and stored on your website visitors’ computers by default when they visit your site.
A first-party cookie will provide information about what users did while visiting your website — how often they visit it and other basic analytics that you can use to help develop an effective marketing strategy.
Third-party cookies are tracking codes that are placed on a web visitor’s computer after being generated by another website other than your own. When a web visitor visits your site and others, the third-party cookie tracks this information and sends it to the third-party who created the cookie — which might be an advertiser.
A great example of the power of third-party cookies
Let’s say you’re getting married and start shopping for wedding paraphernalia — caterers, dresses, flowers, shoes, jewelry, photographers, etc. You pull up Amazon to start researching availability and costs, viewing a lot of items, and spending time on a number of product pages.
Exhausted from this effort, you pour a glass of wine, purchase a pair of shoes and take a break. Now you start receiving emails and ads for dresses, flowers, caterers, bakeries, and jewelry that you looked at on Amazon but didn’t purchase.