P Switch

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

Super Mario Bros. 3
In Super Mario Bros. 3, a P Switch can cause the animations of Question Blocks, Brick Blocks, Jump Blocks, and Coins to stop. In addition, item-holding Brick Blocks changed to look like Coins (but still acted normally); Super Mario Advance 4: Super Mario Bros. 3 fixed most of these errors.

Super Mario World
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, as gray P Switches don't appear in Super Mario Bros. 3, and Jelectros don't appear in Super Mario World. 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.

Mario & Wario
In Mario & Wario, Switch Blocks do not have their "P", but they switch between solid (red) and intangible (blue).

New Super Mario Bros. series
In New Super Mario Bros., New Super Mario Bros. Wii, New Super Mario Bros. 2, and New Super Mario Bros. U (including its expansion pack New Super Luigi U), some P Switches can be reused. Prior to these games, all P Switches become unusable indefinitely after one activation.

Super Mario 3D Land
P Switches appear in Super Mario 3D Land, where they are flatter with a light blue "P" printed. When pressed, they become red. Unlike in previous games, P Switches work more like the ? Coins of the Super Mario Galaxy games.

Super Mario 3D World
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. In addition to their effects from 3D Land, they can once again spawn Blue Coins. There are also square panels with a white "P" that have similar effect to P Switches, although more than one often has to be pressed at a time to activate the effect. They can be activated by other methods than just the player.

Super Mario Odyssey
P Switches appear once again in Super Mario Odyssey.

Super Smash Bros. for Nintendo 3DS / Wii U
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.

Captain Toad: Treasure Tracker
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.

Super Mario Maker / Super Mario Maker for Nintendo 3DS
P Switches reappear in Super Mario Maker and Super Mario Maker for Nintendo 3DS, retaining their functions of changing Brick Blocks to Coins and vice versa. They also stop conveyor belts from moving, as they did in Super Mario Bros. 3. They can also be carried like in Super Mario World, which applies to the other styles except Super Mario Bros., where Mario couldn't carry objects. An update on December 21, 2015 introduced P Doors. These blue doors act as a normal Warp Door, but are only usable when a P Switch is activated. When a P Switch is shaken in edit mode, it transforms into a key.

They can be used in all four styles, retaining their designs in Super Mario Bros. 3, Super Mario World (blue version) and New Super Mario Bros. U, after the 1.30 update. During the original release, the P-Switch was colored as orange with a brown P in the Super Mario Bros. style, while ? Switches appeared in the New Super Mario Bros. U style, instead of P-Switches. The update changed both switches back to the original P Switch appearances from the other games, although the coloring in the New Super Mario Bros. U style is closer to dark blue than the original's cyan.

Effects
When pressed, a P Switch makes a change in the stage for a limited amount of time. This includes:
 * Turning Brick Blocks, Empty Blocks (in Super Mario World), and Rotating Blocks (in Super Mario Maker 's Super Mario World style) into Coins or vice versa.
 * Changing enemies into Silver Coins (Super Mario World gray switches only)
 * Turning Munchers into Coins (Requires gray switch in Super Mario World.)
 * 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 ? Blocks appear. (Super Mario World)
 * Stopping conveyor belts from moving (Super Mario Bros. 3 and Super Mario Maker)

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.