A cookbook or cookery book is a kitchen reference containing recipes. Cookbooks may be general, or may specialize in a particular cuisine or category of food. Recipes in cookbooks are organized in various ways: by course, by main ingredient, by cooking technique, alphabetically, by region or country, and so on. They may include illustrations of finished dishes and preparation steps; discussions of cooking techniques, advice on kitchen equipment, ingredients, tips, and substitutions; historical and cultural notes; and so on.