Dynamic Audiences are audiences build based on Interactions users have had with your products or your websites.
Whether it is a user that purchased something from you that you want to up-sell, or someone that went to the step of adding a product to their cart, but did not end up buying, you can target them again to push them further down the conversion funnel.
Be aware that for Dynamic Audiences you'll need both Catalogs and a Pixel that has tracked user actions. These are going to be the source of all of your Audiences.
Why are they Dynamic?
Any interaction from users with your products, website or content will be tracked, and will design the Dynamic Audience further, reaching more people in the future!
Learn how to use them here!