In singles match play, back in the day, if an opponent's ball was in the way of your ball, but more than six inches away from your ball, it was not lifted. You were just out of luck. Your options would be to slice or draw your putt around the ball in the way, or chip or pop your ball up over the offending ball.
If the opponent's ball was in your ball's way, but the balls were within six inches of each other, then the offending ball was lifted.
If your ball struck your opponent's ball, your ball would be played as it lie. But your opponent would have the option of putting his ball from its new position, or replacing it at its previous position. And if your ball knocked your opponent's ball into the cup, your opponent was considered to have holed out.
You can still occasionally catch footage of players dealing with stymies in broadcasts of pre-1952 match play matches, such as the PGA Championship.
Beginning in 1952, stymies were eliminated from the Rules of Golf.
