So Product Catalogs, or Feeds, is simply a file that contains all of your product data in a specific format that all the big players in Dynamic Product Retargeting can read. These files allow you to run DPA or Display Product Ads and require advanced matching between your pixel/event traffic source and the product catalog.
Building a Product Catalog can be rather difficult, if you have a ton of products the files can get quite large and complex to manage, you always have to meet specific criteria which will vary from platform to platform. You also need to consider that the images used on your website may not be the best image to use for your dynamic retargeting, so there is a lot to consider.
That being said, there are also a ton of plugins and platforms that make this far easier, from simple plugins which are super affordable and accessible to entire enterprise services like Feedonomics which provide feed management support & services, however, these have a much higher barrier to entry – with scaling costs based on SKU but an entry price of around $750 – $1K/month.
Depending on the number SKU’s and type of products or service you offer – dynamic retargeting based on SKU or Product View event might not be the best for you, but for the most part any e-commerce store will want to implement some sort of catalog or product feed to get DPA ads out across Facebook and the Google Display Network (GDN).