Hermitian matrices have real eigenvalues.
Hermitian matrices have one eigenvector for each eigenvalue (except for degeneracy).
The eigenvectors of a Hermitian matrix are orthogonal and can be normalized, i.e. they are orthonormal.
The eigenvectors of a Hermitian matrix form an orthonormal basis for the space of all vectors in the vector space.
Commuting operators share the same eigenbasis.