The Senior Open Championship, or simply The Senior Open (and originally known as the Senior British Open) is a professional golf tournament for players aged 50 and over. It is run by The R&A, the same body that organises The Open Championship, and is usually held the week following The Open Championship. Prize money won in the event is official money on both the Champions Tour and the European Seniors Tour. The purse, which is fixed in United States dollars, was $2 million in 2011, with a winner's share of $315,600. For sponsorship reasons, it is currently known as The Senior Open Championship presented by Rolex.
The tournament was first held 28 years ago in 1987 and became part of the European Seniors Tour schedule in 1992. In late 2002 it was designated as the fifth major championship on the Champions Tour schedule. All winners before 2003 were not retroactively designated as Champions Tour major winners. Winners gain entry into the following season's Open Championship.
The standard field size is 144 players and an 18-hole qualifying round is held at the championship course on the Monday before the tournament, with a minimum of 24 places available. If fewer than 120 exempt players (see below) enter, the field is filled to 144 with more high finishers from qualifying. If more than 120 exempt players enter, the top 24 finishers earn entry even if it causes the field to expand beyond 144. If an exempt player withdraws before the start of the tournament, his place is filled by an alternate who participated in the qualifying round.
Currently, the following players are exempt from qualifying for The Senior Open, provided they are 50 years old as of the opening day of the tournament. Amateur categories require that the player is still an amateur on the opening day of the tournament.