## What is the C^1 domain? [closed]

Hi

I just came across the Deufelhard & Bornemann text on Scientific Computing with ODEs where they write, for example:

$f \in C(\Omega, \mathbb{R}^d)$

in other places they use $C^1(\cdot,\cdot)$.

Easy question: what does the $C$ / $C^n$ refer to?