Seven-layer salad is an American dish that includes a colorful combination of seven layers of ingredients: iceberg lettuce, tomatoes, cucumbers, onions, sweet peas, hard boiled eggs, sharp cheddar cheese, and bacon pieces. The salad is topped with a mayonnaise-based dressing and sometimes sour cream is added. It is served in a glass bowl or large pan so the layers can be observed. The dish is often associated with potlucks, picnics, and barbecues, where a large gathering of people takes place and many people need to be fed. There are many variants on the seven-layer salad and it can be made with additional (or sometimes fewer) layers, making it (for example) an eight-layer salad instead.