Cheese is a food made by curdling milk with special bacteria and enzymes, then aging it until it becomes solid. The process transforms liquid milk into everything from soft, spreadable cream cheese to hard blocks of cheddar or Parmesan that you can grate over pasta.

People have been making cheese for at least 4,000 years, and nearly every culture that raises dairy animals has its own varieties. The French make over 300 types of cheese, from creamy brie to pungent Roquefort. The Swiss are famous for holey wheels of Emmental. Americans produce sharp cheddar, Monterey Jack, and processed cheese slices.

The word cheese also appears in some interesting expressions. When a photographer says “say cheese!” before taking a picture, they're trying to make you smile (saying the word naturally pulls your mouth into a grin). Something cheesy can mean literally covered in cheese, like a cheesy pizza, but it also describes something embarrassingly corny or trying too hard to be funny or sentimental, like a movie with cheesy dialogue or a cheesy magic trick.