In most team tournaments there will be a number of players, usually four plus one reserve in the case of the olympiad, and a team captain. Of course the players play but what of the team captain? What is his/her role?
In my opinion the following are the responsibilities of the captain though this is not really set in stone and readers might have different opinions.
1) Submit the team line-up for the next round. This is probably the most important task. The captain should consult his team and decide who is to play and who is to rest. The decision should be a collective one and in event of disagreement the captain should make the final decision. This is not as simple as it seems. In my experience, everyone wants to play when paired with a weaker team.
2) Liase with the arbiter and organizing committee. The captain represents the team at any meetings. The captain also submits appeals when the situation necessitates.
3) Advise a player to offer a draw. This should be based on the tournament situation and not the actual board position. This is especially important now that match points are increasingly used. A classic example was the last round of the 2008 Dresden olympiad. A draw in the last game would have given us the match win. Mok continued to play and eventually blundered and lost thereby giving us only a tie. This dropped us several positions in the final standing.
4) Now that the zero start rule is enforced, the captain should ensure that all the boards are present before the start of the round. This may seem quite trivial but you would be surprised how many players forfeited at the last olympiad due to not being present at the board.
5) The captain has to be present to sign off the full results at the end of the match. I think this rule is not that strict and a player may sign on behalf of the captain.
6) Maintain team spirit and morale.
What makes a good captain? An ideal team captain is someone who has the respect of all team members, have some chess playing skill, good people management skill and ability to keep a team together.