P Switch

P Switches (also known as Switch Blocks, alternatively written P-Switch) are items found in several Super Mario games such as Super Mario Bros. 3, Super Mario World, New Super Mario Bros., and Super Mario 3D Land.

When pressed, a P Switch makes a change in the stage for a limited amount of time. This includes:
 * Turning Brick Blocks (used Blocks in Super Mario World) into coins or vice versa.
 * Changing enemies into Silver Coins (Super Mario World gray switches only)
 * Turning Munchers and Jelectros into coins (Requires gray switch in Super Mario World, but was never used for Jelectros as they don't appear in said game.)
 * Allowing Mario to access a hidden door (Appears as a white light in remakes of Super Mario Bros. 3, a blue door in Super Mario World and a blue door with a P in Super Mario Maker. Appears as a normal door in all other games.)
 * Making hidden Coins appear (Silver Coins in Super Mario Bros. 3 and New Super Mario Bros.; Blue Coins in other games)
 * Making hidden Question Blocks appear. (Super Mario World)
 * Stopping conveyor belts from moving (Super Mario Bros. 3)

Sometimes, a Brick Block with an item inside resembles a coin, but acts as a block. This is fixed in the Game Boy Advance remake of Super Mario Bros. 3.

In Super Mario Bros. 3, a P Switch can cause the animations of Question Blocks, Brick Blocks and Jump Blocks to stop. In addition, reversed coins and bricks don't have any animation (except in Super Mario Advance 4: Super Mario Bros. 3).

In Super Mario World, the gray version of the P Switch makes most enemies turn into Silver Coins. Collecting eight of these coins awards Mario an extra life. Collecting one more gives Mario two extra lives. After nine coins, Mario will earn three extra lives for each additional coin. Also, gray P Switches can turn Munchers and Jelectros into regular coins, however, there was no original level that featured both Jelectros and a P Switch at the same time. Super Mario World is the only game in which P Switches can be carried by Mario and saved for later. (Mario can also carry the switch after it has been pressed for a short time if he's quick before it disappears.) In all other games, Mario can't carry the switches and must use them right where they appear.

In Mario & Wario, Switch Blocks do not have their "P", but they switch solid and non-solid colors.

In both New Super Mario Bros. and New Super Mario Bros. Wii, some P Switches could be reused. This is the first instance of P Switches exhibiting this characteristic. Prior to this, all P Switches became unusable indefinitely after one activation.

P Switches appear in Super Mario 3D Land. Here, they are flatter with a light blue "P" printed. When pressed, they become red.

P Switches also appear in New Super Mario Bros. 2 and New Super Mario Bros. U (including its expansion pack New Super Luigi U), where they serve the exact same functions as in the previous New Super Mario Bros. games.

P Switches appear in Super Mario 3D World. They have the same appearance as they do in Super Mario 3D Land, but with a white "P"; they don't change colors when pressed.

A P Switch makes its first appearance outside the Super Mario series in the Golden Plains stage in Super Smash Bros. for Nintendo 3DS. If a fighter steps on one, Blue Coins will temporarily appear among the ordinary Coins while the P Switch music plays over the stage music, as in the New Super Mario Bros. series. A P Switch also appears as a Trophy.

P Switches also appear in Captain Toad: Treasure Tracker. They are generally used to alter the layout of the stage, allowing the player to progress.

P Switches reappear in Super Mario Maker, retaining their functions of changing Brick Blocks to Coins and vice versa. They can be used in all four styles, retaining their designs in Super Mario Bros. 3 and Super Mario World (blue version), appearing in the Super Mario Bros. style, coloured as orange with a brown P, and as ? Switches in the New Super Mario Bros. U style. They can also be carried like in Super Mario World, which applies to the other styles except Super Mario Bros., where they couldn't be carried in the original games. An update on December 21, 2015 introduced P Warp Doors. These blue doors act as a normal Warp Door, but are only usable when a P Switch is activated. The update changed the yellow P Switch in the Super Mario Bros. style and the ? Switch in the New Super Mario Bros. U style back to the original P Switch appearances from the other games.

Trivia

 * Before the announcement of the 1.3.0 update for Super Mario Maker, the original blue design of the P-Switch in the Super Mario Bros. style was accidentally leaked through the preview screenshot of the Mercedes-Benz Jump'n'Drive Event Course.