\begin{definition}[Definition:Homeomorphism/Topological Spaces/Definition 3]
Let $T_\alpha = \struct {S_\alpha, \tau_\alpha}$ and $T_\beta = \struct {S_\beta, \tau_\beta}$ be topological spaces.
Let $f: T_\alpha \to T_\beta$ be a bijection.
$f$ is a '''homeomorphism''' {{iff}} $f$ is both an open mapping and a continuous mapping.
\end{definition}