Glazed tile is a type of porcelain tiles to which a glaze has been applied. After the glaze is painted or sprayed on, the tile is fired at high temperatures, causing a chemical reaction which makes the glaze vitrify, essentially turning into glass. The resulting tile is resistant to water and stains because of the glaze, and it has an attractive look, as a wide variety of colors and designs can be created with glaze, with finishes ranging from extremely glossy to matte.
There are a number of advantages to glazed tile. One of the most obvious is that these tiles do not require sealing from water, because they are already sealed; if a watertight grout is used to lay a glazed tile floor, the floor will not need to be sealed and then resealed as the sealant wears off. Glazed tiles can also come in a range of textures, from more coarse matte tiles which are good for flooring since they provide traction to high gloss, very smooth tiles which work well for countertops and backsplashes.