Also known collectively as gadrooning, these are the modification of columns or walls with vertical grooves and ridges. It’s something right out of Classical architecture, and is often a decorative tool that is deliberately used to invoke that period.

The technique is used to influence the play of light, and helps a column appear more perfectly round than an actual cylinder with small imperfections. They’re also supposed to emphasise the axial dimension.
So I was intrigued when I saw this tile collection that assembles to form the impression of fluting and reeding. The principle of modularity seems so far away from this Classical embellishment, which emphasises an element’s continuity and perfection of the whole.
It’s still very visually pleasing, but the visible separation between tiles constantly reminds me that the designer is making a play on its rhythm.