The US Open golf tournament uses a par system, where each hole's difficulty is assigned a par based on its length.
Oakmont Country Club, this year's venue, has a par of 70 for 18 holes, meaning a score of 70 is considered even par.
Players' scores are calculated relative to this par; scoring below par results in a negative score, above par a positive score.
The tournament employs a stroke play format, meaning players compete based on their total number of strokes across all rounds and against each other.
