For the most part, the US Open follows standard golfing rules. The only real difference is in how tie-breakers work. Until now, in the event of a tie, golfers played 18 holes, after which, the player with the lowest stroke count would win. However, there was one rule change a few years back.
Now, tied players will compete across two holes. If one person has the lowest score overall, they win. If two or more players tie after these two holes, they’ll go into sudden death. This means that they’ll play one additional hole at a time until a single victor remains.