> [!definition] > > Let $A \subset \real^n$ and $\seqf{\xi_k}$ be a family of [[Vector Field|vector fields]]. The family $\seqf{\xi_k}$ is orthonormal if for every $p \in A$, $\seqf{\xi_k|_p}$ is [[Orthonormal Set|orthonormal]]. If they form a [[Frame|frame]], then they are an **orthonormal frame**.