What exactly is isospin and what does it have to do with the strong force?
Wikipedia is your friend: http://en.wikipedia.org/wiki/Isospin
Perhaps you've read that page and have some more specific question?
protons and neutrons behave similarly owing to strong interaction between them.Isospin is used to give both proton and neutron, a quantum number.+1/2 and -1/2 but the opposite is also used in literature.You can see landau's book 'non-relativistic quantum mechanics' for an accessible account of it.
Separate names with a comma.