Definition: A key or legend is a list of symbols that appear on the map. For example, a church on the map may appear as a cross, a cross attached to a circle, a cross attached to a square. A church symbol with a square means that the church has a tower, while a circle means the church has a spire. The symbol PH means Public House, or pub. The symbol Sch means School. Symbols and colours can also represent different things like roads, rivers and land height.