Tiles tend to expand in heat and contract in lower temperatures. If no space is left between consecutive tiles, it may lead to either cracking / debonding of tiles due to expansion / contraction. Hence, there should be some filler material between the tiles that provides room for expansion / contraction of tiles. This material is called grout. They can be either cementitious or epoxy based.

Cement based grout is cheaper than epoxy based. It can be used where water ingression, chemical attacks and hygiene is not an issue. Epoxy based grout is highly durable, resistant towards chemicals attacks, resists water ingression and prevents growth of tiny insects.