Although golf is usually a solitary sport, amateurs often play as teams. Even professional golfers enjoy team play every now and then, as witnessed by the Ryder Cup and Solheim Cup competitions. One popular format in team play is two-man best ball, sometimes referred to as "better ball," although the United States Golf Association uses neither name. The USGA's Rules of Golf do provide rules for this popular team format.
Clearing Up the Terms
The USGA doesn't use the term "two-man best ball" at all. The Rules of Golf define "best ball" as "a match in which one player plays against the better ball of two other players or the best ball of three other players." And although the term "better ball" is sometimes used in the Rules of Golf (as in the best-ball definition), the USGA uses it as a comparative term and not as a form of play. This format is officially called "four-ball" in the Rules of Golf.
Formats and Rules
Four-ball can be played as either match play or stroke play. In four-ball, there are two teams of two players in each group; hence, there are four balls in play. You and your partner form one "side." In match play, your side competes solely against the other side in your specific pairing. In stroke play, both sides in your pairing are competing against all of the other sides in the event. Although the regular Rules of Golf generally apply to four-ball, the team aspect creates some unusual situations which the normal rules were never meant to address; therefore, Rule 30 (covering four-ball match play) and Rule 31 (covering four-ball stroke play) outline the conditions that override the normal rules.
Whether in match or stroke play, you and your partner play your own golf balls on each hole. At the completion of each hole, the two of you select your lowest stroke total; that becomes your side's official score. In stroke play, that score is added to your side's total round score. In match play, your side's score is compared against the other side to determine which side wins the hole. The Rules of Golf do not specify a specific order of play for your side. You and your partner may play in any order you decide is best. One important point is that, as long as one of you can post a score, the other need not even finish the hole. Only one player has to finish the hole for your side's score to be official.
For the most part, penalties follow the normal Rules of Golf. Because there are two players on each side, one player can be penalized without affecting the other's score. In fact, sometimes one player can be disqualified without the side being disqualified. Rules 30 and 31 specifically define when the side must be disqualified, as well as the individual penalties each player can incur in the four-ball format.