At the opening of the 21st century, the classic brown and white sauces have become scarce, so much so that perhaps we’re ready to appreciate their virtues again. Those restaurant and home cooks who do serve time-consuming meat stocks and reductions seldom make them from scratch; these products are well suited to manufacture on an industrial scale, and good versions are available in frozen form. The rich cream and butter sauces popularized by the nouvelle cuisine have become less common; simpler broths, reduced pan deglazings, and vinaigrettes more so. Thanks to the international scope of modern cooking, restaurant diners encounter a wider range of sauces than ever before. Many of them are contrasting purees made from fruits, vegetables, nuts, and spices, or else thinner soy- and fish-based Asian dipping sauces; these are attractive to restaurateurs because they require less time, labor, and often less skill than the classic French sauces. Similarly, home cooks are now likely to buy time-saving and versatile bottled sauces and dressings. And a few inventive chefs are experimenting with unusual tools and materials—among them liquid nitrogen, high-powered pulverizers, thickeners derived from seaweeds and microbes—to make new forms of suspensions, emulsions, foams, and jellies.