This is kind of a newbie question, but I'll ask it anyway. This arises from my reading of a post regarding whether Beckham ought to stay on as England's captain. The discussion seemed to be focused on a lot of pros and cons that apparently go into the calculus for determining who should be captain - leadership, credibility, scoring, on-field performance, etc. Having never played the game competitively, I am pretty ignorant regarding what the captain does and what it takes to be one. I am familiar with what a captain does in American football and basketball, but what does a captain do in soccer, and what makes a good captain?