a bit of additional info.its a cut and paste job from wikipedia...but it seems to answer some questions nevertheless
"In mathematics, especially in the area of abstract algebra known as ring theory, a domain is a ring such that ab = 0 implies that either a = 0 or b = 0.[1] That is, it is a...
My understanding is that a unity element is a prerequisite for defining an integral domain in general. However as Herstein shows in the proof for the theorem that every finite integral domain is a field, its easy to show the inherent existence of an unity element in an integral domain when its...