One of the primary differences between stroke play and match play is that a player must hole out on every hole in stroke play to record an overall score for his or her round. Match play allows for concessions, meaning that a player does not necessarily need to hole out on every hole.
During the 1962 U.S. Open at Oakmont (Pa.) Country Club, hometown hero Arnold Palmer and Jack Nicklaus were tied after 72 holes. They squared off in an 18-hole, stroke-play playoff the following day (Historical note: The playoff took place on Sunday, as until 1965, the championship’s final 36 holes were played on Saturday). After Palmer missed his first putt on the final green of the playoff, he knew that victory was out of reach and picked up Nicklaus’ ball marker to concede defeat and congratulate him, as can be seen in the video clip above.
Even though the outcome was a foregone conclusion, this was a stroke-play competition, and therefore Nicklaus was required to hole out. The Rules official on hand intervened, asked Nicklaus to replace his ball marker and finish out the hole. Palmer did not incur any penalty for this action because the Rules did not prescribe a penalty for a ball at rest moved by a fellow competitor in stroke play. The same outcome would occur today under Rule 18-4.
A stroke-play competition between only two players is rare, and Palmer’s action of picking up Nicklaus’ ball marker likely came from the tendency to think of a one-on-one situation more as match play than as stroke play. His near-miss at Oakmont was one of four second-place finishes in the U.S. Open for Palmer. Nicklaus’ victory was his first of four U.S. Open triumphs.
http://www.usga.org/articles/2017/01/rules-throwback–not-so-fast–jack.html
Source: USGA.org