What is the significance of parity in particle physics?

[JoePhysicsNut]

The parity operator has eigenvalues of +/- 1 and particles can have intrinsic parity of +/- 1. What does it matter? Does a P=-1 particle behave physically different from a P=+1 particle?

Is parity a useful concept only in the sense that one can check if an interaction conserves parity (parity of final state particles is same as parity of initial state particles) or not and then conclude something about the nature of the coupling (the mathematical form of the vertex factor, say)?

 

[mfb]

Is parity a useful concept only in the sense that one can check if an interaction conserves parity (parity of final state particles is same as parity of initial state particles) or not and then conclude something about the nature of the coupling (the mathematical form of the vertex factor, say)?

Parity is useful there. The electromagnetic and strong interaction conserve parity, for example.
The Tau Theta puzzle is an interesting example how parity considerations lead to new insights.