A comb is the fleshy, red outgrowth on top of a chicken's head. Types of combs, shown below, include single, rose, pea, cushion, strawberry, buttercup, and V-shaped. The comb primarily is for display, but it also serves to cool the bird in hot weather. In hens, the comb is an indicator of egg production status. A large, red comb typically indicates a hen that is laying eggs; a small, pink comb indicates a bird that is not laying.
Different types of chicken combs. Source: University of Illinois. Used with permission.