Density estimation is a way of trying to figure out how big something is. For example, if you have a bag of candy, you can count how many pieces of candy are in the bag, but with density estimation, you can figure out how big the bag is. It can also be used to figure out how dense something is, like a piece of metal or a gas. Basically, density estimation tries to figure out the volume (how big something is) or the mass (how heavy it is) of an object or material by looking at how many particles or atoms it has.