Here in the UK (especially after you've been employed for over two years and/or you're off "probation") it tends to be the last step in a long process of verbal then written warnings where you're repeatedly doing things you're getting told off for. Relatively few things are actually "bad" enough to get you instantly dismissed on the spot (theft and the woolly term "gross misconduct" jump to mind, but even then there were multiple meetings, investigations and very specific charges).
In the UK if you were fired (rather than being made redundant or being given the chance to quit) it tends to mean that the blame is on you, to the point where the company would be willing to prove this with evidence at a tribunal (-especially if it's a medium to large company).
From what I'm reading, in the US it seems to be a case that you could loose your job, with no notice at any time for any reason?