Should governments allow "hate speech"? Why or why not?

This thread is for the discussion of whether governments should or should not allow hate speech. Some argue that governments should allow it, as preventing it doesn't prevent discrimination. Some argue that hate speech is incitement to violence and that is why it should be disallowed. Is it? What is the distinction then between "hate speech" and "incitement to violence? Why or why not should hate speech be allowed/disallowed?