Waterline tile
Also called: tile line, waterline band, pool tile.
Waterline tile is the band of tile at the waterline that almost every pool has, whether the surface below it is plaster, pebble, fiberglass or full tile. It is the most-seen strip of the pool and takes the worst of the scale, oils and sun.
Why it matters
For most pools the real choice is porcelain or glass. Porcelain is clay fired hot and dense, absorbs almost no water (well under 1%), is frost-proof, resists scale and stains, and is more forgiving to install. Glass is the premium look, with color all the way through and a surface impervious to water, chemicals and UV, but it needs a skilled installer, shows calcium scale more, and must never be scrubbed with a pumice stone. Natural stone is porous, needs sealing and etches in aggressive water. Mosaic is small tile on mesh, not a material. The lasting fix for scale on any tile is water balance, not scrubbing.
In numbers
Glass tile belongs at the waterline, on walls, on a spa spillover or on a raised feature wall. It never goes on floors, steps, benches or any surface where people walk.