Motivation of the definition of Euclidean Domain We know the definition of Euclidean Domain is

An Euclidean Domain is an Integral domain $(E,+,\ast )$ together with a function $v: E\setminus \{0\} \to \mathbb{N} \cup  \{0\} $ such that
(i) for all $a,b \in E$ with $b \neq 0$, there exist $q,r \in E$ such that $a = qb + r$ ,where $r=0$ or $v(r) \lt v(b)$
(ii) for all $a,b \in E \setminus \{0\}$, $v(a) \leq v(ab)$.

What is the motivation behind the definition of Euclidean Domain. Is it a generalisation of something?

The motivation comes from a strong property of natural (and integer) numbers: the Euclidean algorithm that allows to find a gcd between two numbers.
The function $v$ is then just a degree function that gives you a weight comparison between these "abstract" elements of the ring. For the integers $v=|\cdot|$, for the ring of polynomial is the degree function.
