Question: What exactly IS a heterocycle?

Florence McCarthy answered on 7 Nov 2015:

A heterocycle is a ring of atoms made from carbon and another element, the most common being nitrogen, sulphur or oxygen. The most common cycle made from carbon is benzene so we make new types of benzene that have some of the carbons replaced by nitrogen, oxygen or sulphur. These are very common in drugs and that why what we do is so important to discovering new drugs.