Islamic art tends to be quite abstract, as it avoids depicting people and animals in case that might be idolatrous, so geometric patterns and abstract floral designs are more common than actual pictures of things.
Something you'll see a lot is tilework (zellij) mosaics, with tiles cut to shapes that fit together to make geometric patterns. You'll typically see this on floors (for example at the El Badi Palace), and on the lower part of walls (for example in the Ben Youssef Medersa, the Bahia Palace, the Saadian Tombs and Dar el Bacha).
Text © Daniel Jacobs
Images by Anna & Michal, Daniel Jacobs, Gareth Williams, jcb2u, Miguel Discart