Most if not commercial swimming pools, apart from gutter-style pools, have coping, tile, and caulk at the top of the pool wall. The main purpose of this masonry is to provide an attractive “pop” to the facility and appear inviting to the pool users.
The general purpose of those pool components is to provide structure, safety, and ease of maintenance. The coping provides an attractive, non-skid surface and hand grip for swimmers. The waterline tile provides and attractive, glazed, or glossy surface that makes the cleaning of dirt and sun oils from the scum line easier than a concrete or painted surface.
Caulking prevents freezing water from gathering in the joint between the pool shell and the pool deck. This is probably the most important of all as here is where most issurs with tiles and coping stones start.