What Do Social Workers Actually Do?

I’m curious about a career in social work. It seems like a very rewarding line of work, because social workers get to help people in all sorts of ways. But when I say all sorts of ways, I mean all sorts of ways – and, to be honest, sometimes I get confused about what social workers actually do. I know some work in schools and others with mental patients, for instance. Is there anything typical of all types of social work? What different things can social workers do?