Smetana is a yummy dairy product that comes from milk. Think of milk as a big white liquid that comes from cows. Smetana is made by fermenting (or letting it sit for a while) sour cream, which is like the creamy white stuff you put on your tacos or baked potatoes. Fermenting means letting good bacteria grow in the sour cream. This is similar to making pickles or yogurt. The bacteria in smetana make it taste tangy and a little bit sour. It's really good on top of potatoes or even with fruit!