Beekeeping is the maintenance of honey bee colonies, commonly in hives, by humans. A beekeeper (or apiarist) keeps bees in order to collect honey and other products of the hive (including beeswax, propolis, pollen, and royal jelly), to pollinate crops, or to produce bees for sale to other beekeepers. A location where bees are kept is called an apiary or "bee yard". The Tacuinum (sometimes Taccuinum) Sanitatis is a medieval handbook on health and wellbeing, based on the Taqwim al-sihha, an 11th century Arab medical treatise by Ibn Butlan of Baghdad.