Honestly, I think it is just the age.
It sucks but all three of mine have gone through this stage at one point or another - my youngest is not much over one, and has started already! He screams, he hits, he bites, he says 'no', he throws tantrums. I am hoping because he hit this stage at an earlier age he may grow out of it quicker? probably wishful thinking

All you can do, in my experience, is be consistant. It is horrible sometimes, all you feel like you are ever doing is handing out punishment after punishment somedays, but consistancy really is the key. I try to use 'praise' as the reward if I can, but have been known to resort to outright bribery on occaision. If I can see something that is likely to become and issue, I try to intervene early and redirect: but even that is hit and miss. The reason people use the rewards / punishment methods, is because they do work (at least sometimes, and in the long term).

But as they say "this too shall pass" (and of course along will come a new challenge) and in the meantime, just remember it IS normal.