A chimney cap is a protective cover placed on top of a chimney. Its primary function is to prevent rain, snow, and debris from entering the chimney, which can cause blockages and damage. Additionally, it helps to keep animals, such as birds and squirrels, from nesting inside the chimney. Chimney caps are typically made from materials like stainless steel, copper, or galvanized metal. They often feature a mesh screen to allow smoke to escape while keeping out unwanted pests. Proper installation of a chimney cap can enhance the efficiency of a fireplace and prolong the life of the chimney structure.