Run a hand across a textured tile and the difference from a flat glaze is immediate. Ridges, grooves, a hammered or stone-like relief, sometimes a full three dimensional pattern, texture gives a surface something to say beyond colour alone. It catches light and shadow in a way a smooth tile never will, adding real depth to a plain wall or floor.
Texture is particularly useful where grip matters, on a shower floor, a boot room, or an outdoor step, since a textured surface generally offers more traction underfoot than a smooth or polished one. On walls, the same texture becomes purely about character, turning a feature wall into something closer to art than background. Textured surfaces do collect a little more dust in the grooves than a flat tile, so a soft brush alongside your usual cleaner keeps them looking sharp.