Margarine, as a generic term, can indicate any of a wide range of butter-substitutes. In many parts of the world, margarine has become the best-selling table spread, although butter and olive oil also command large market shares. Margarine is an ingredient in the preparation of many other foods. In informal speech people commonly refer to margarine as butter, but (at least in the United States) laws forbid food packaging to refer to margarine as "butter". Recipes sometimes refer to margarine as oleo or as shortening.
Margarine is available in bricks, like butter and in spreadable form, so-called "soft margarine".