[Urbanium]

Hi, I am a quantum chemistry noob and I do have one question: when somebody says that quantum mechanics is used to predict and explain the reactivity of organic molecules, what does it mean?

Does it have to do with Hartree-Fock, Huckel method, DFT...? Which quantum chemistry methods in particular are used to explore reactivity?

I would also appreciate if somebody could recommend some software used exclusively for that kind of calculations.