Ketchup, or catsup, is a table sauce. Traditionally, different recipes feature ketchup made of egg white, mushrooms, oysters, mussels, walnuts, or other foods,^[1][2] but in modern times the term without modification usually refers to tomato ketchup, called tomato sauce more commonly in Australia, New Zealand, and India and almost exclusively in South Africa. (“Tomato sauce” can also mean something more like Passata.) Ketchup is a sweet and tangy sauce, typically made from tomatoes, a sweetener, vinegar, and assorted seasonings and spices. Seasonings vary by recipe, but commonly include onions, allspice, cloves, cinnamon, garlic, and sometimes celery.^[3] Heinz tomato ketchup is the market leader, with an 82% market share in the UK and 60% share in the US.^[4][5]

Tomato ketchup is often used as a condiment with various dishes that are usually served hot, including chips/fries, hamburgers,sandwiches, hot dogs, eggs, and grilled or fried meat. Ketchup is sometimes used as a basis or ingredient for other sauces and dressings, and is also used as an additive flavoring for snacks such as potato chips.