What is the difference between a Bell state and a Bell measurement? I am studying quantum computation, and Bell states have been introduced. I understand that Bell states can be prepared using the CNOT gate with various inputs, but it's not clear what a Bell measurement is. The reason I ask is that it came up in discussion without any explanation of what was meant by measurement!
For instance, if I prepare a bell state $ |\Psi_- \rangle$, what can I "measure?" What form do these measurements take? If possible, an answer in terms of quantum teleportation would be super helpful.
Speculation: It seems that perhaps all I can really measure are other, unknown, bell states, but I have general relativity diagrams from lecture that seem to indicate bell measurements can be performed on states of the form $| \psi \rangle = \alpha |0 \rangle + \beta |1 \rangle $. Any additional clarification in this regard is greatly appreciated.