Parametrising the boundary of an open ball

Question

I have been asked to evaluate line integrals of complex functions, namely of the form $$\int_{\gamma} f(z) dz$$ where $f: U \rightarrow \mathbb{C}$ is an analytic function and $\gamma : [t_{0}, t_{1}] \rightarrow U$ is a curve. and to do this we need to parametrise the curve $\gamma$. So my question is how exactly would we parametrise the boundary of an open ball $B_{r}(a)$?