A mixture of plant material -- usually vegetables, though many fruit salads are very popular -- which can be eaten by people. A salad can be a side dish, an entree, or even a dessert. A salad can be topped by salad dressing, croutons, bacon bits, cheese, and other edible substances designed to improve the taste. Many salads have a pasta base -- vegetables are present, but pasta salads are generally just an excuse to eat some fancy noodles.
Ideally, a salad should include lettuce, onions, black olives, peppers, a little cheese, a small handful of croutons, and either Ranch or Bleu cheese dressing. Tomatoes should be avoided, as they are the Food of the Devil.