Cheese curds are the parts of cheese left over after making, well, cheese. They’re often produced in mass quantities in the cheese making process. In dairy states such as Minnesota and Wisconsin, pople would eat these by-products raw or they would cook them in various ways.
In 1975, at the Minnesota State Fair, cheese curds became a main food (not just a byproduct). They became a perennial star of the food scene:
When people move away from MN, they often experience cravings for deep-fried cheese curds and they will try to make them on their own. Here is a recipe
They should look like this: