Foursomes are the matches played on the Friday and Saturday of the Ryder Cup and there are four matches on each day.
The schedule has been changed this year so that foursomes will be played in the afternoons instead of the mornings.
The teams send pairs of players out against each other. The pairings are carefully chosen by the non-playing captain and he can use whichever combination of players he believes will get the right result for his team.
There is no obligation on the captain to choose every player at some stage in either the foursomes or the fourballs contests.
Only one ball is used by each pairing in foursomes. For example, if Tiger Woods is paired with David Duval, Woods would tee off on a par four, Duval would hit the approach to the green and then Woods putts first, before alternating putts with Duval until the hole is completed.
On the next hole, Duval would tee off, irrespective of who had the last putt on the previous hole as one player tees off on the odd holes, the other the evens.
The team with the lowest score wins the hole.