In match play, to concede a hole means that one player recognises the hopelessness of competing further (on this hole) and picks up the ball without holing out. Of course, this awards the hole to the adversary. But it is considered good sportsmanship.

To concede a putt means to permit a competitor to pick up his/her ball when the outcome of a very short putt is not in doubt. In match play, conceding a putt is sometimes used as a competitive tactic. Here's why:

By conceding your competitor those two-foot putts early in the round, your adversary fails to build up confidence by sinking those "gimmee" putts. So late in the round, you can all of a sudden not concede a shorty, forcing your foe to face an unexpected test of nerves.