There are several time settings out there. For example, blitz chess
usually
allows 5 minutes (or even less! I've seen 1 minute games) for the whole
game. An usual setting for tournaments is 2 hours and a half for the
first
40 moves and another hour for the rest of the game (IIRC, there are a lot
of settings).
The player with no time does not automatically lose, his opponent must
notice the fact to claim his win. Furthermore, if the opponent of the
player with no time has only his king remaining, being called for time
will result in a draw, rather than a loss.