  We discuss the concept of how entanglement changes with respect to different
factorizations of the total algebra which describes the quantum states.
Depending on the considered factorization a quantum state appears either
entangled or separable. For pure states we always can switch unitarily between
separability and entanglement, however, for mixed states a minimal amount of
mixedness is needed. We discuss our general statements in detail for the
familiar case of qubits, the GHZ states, Werner states and Gisin states,
emphasizing their geometric features. As theorists we use and play with this
free choice of factorization, which is naturally fixed for an experimentalist.
For theorists it offers an extension of the interpretations and is adequate to
generalizations, as we point out in the examples of quantum teleportation and
entanglement swapping.
