A P-Switch is a blue switch found in Mario games. It first appeared in Super Mario Bros. 3. When Mario steps on it, it will trigger something to happen. It may turn all Brick Blocks in Coins or vice-versa. It can also make groups of Blue Coins appear. There is also a time limit for it. There are two other switches as well like the ! Switch and the ? Switch. The ! Switch can create Red Blocks, it is also known as the Red Switch or Magenta Switch. The ? Switch will make events happen like blocks breaking, creating new floors or creating new areas.
The P Switch appears in Super Mario Moose as an item. In this game it creates blue coins for a limited amount of time that the player can collect. It mainly only appears in bonus sections of levels.
P Switches appear again in Super Mario Moose Deluxe, where they act the same as in Super Mario Moose.