In the United States, a slow cooker is commonly referred to as a "Crock-Pot." "Crock-Pot" is actually a brand name that has become synonymous with slow cookers, similar to how "Kleenex" is often used to refer to facial tissues. The brand Crock-Pot, owned by Sunbeam Products, popularized and commercialized the concept of slow cookers in the 1970s.
Since then, many other brands have started producing similar devices, but the term "Crock-Pot" remains widely used to describe any type of slow cooker in American colloquial language. So, when Americans talk about using a slow cooker, they might say "I'm going to put this in the Crock-Pot" even if the appliance they are using is not an actual Crock-Pot brand slow cooker.