A chocolate chip cookie is a drop cookie that contains pieces of chocolate mixed into the dough before baking. Texture and appearance vary with ingredients and preparation, ranging from moist, chewy cookies to ones that are crispy. Chocolate chip cookies are closely associated with the United States, where they are the most popular cookie. Their invention is generally credited to Massachusetts chef and hotelier Ruth Graves Wakefield in the 1930s, although versions existed that preceded hers.