Jumping

Jumping is a mechanic that elevates the player $1 1/4$ block into the air. It also has other effects when combined with another forms of movement.

Activation
Jumping is done by pressing the jump key (which defaults to the space bar on PC) or the jump button on other devices (for example the 'A' button on Xbox). If auto-jump is on the player jumps whenever they brush up against the edge of a block.

Usage
Jumping normally lets the player climb up 1$1/4$ block. Players with Jump Boost I are able to jump 1$15/16$ block, and with Jump Boost II they are able to jump 2$1/2$ blocks. The effect also increases more with more levels of Jump Boost.
 * Jump height changes

Honey blocks make players jump $3/16$ of a block from them, meaning that they get an 85% jumping reduction.

Cobwebs and sweet berry bushes prevent players from jumping from them.
 * Cancellation

Sneaking and crawling, when activated by suffocation prevention $$, prevent players from jumping due to the reduced space. These two actions normally do not prevent players from jumping.

Jumping can be combined with sprinting to increase the player's movement speed. A single jump while sprinting costs four times as much hunger as a normal jump.
 * Combinations

Mobs
Most land-based mobs are able to jump when they are walking up blocks. However, they do not jump spontaneously, except in these cases:
 * Illagers and witches when celebrating a successful raid
 * Foxes, when attacking
 * Spiders and cave spiders, when attacking
 * Rabbits, as part of their normal movement
 * The killer bunny attacks similarly to spiders
 * Slimes and magma cubes, as a part of their normal movement

These mobs are able to walk up full-sized blocks without jumping:
 * Horses and their variants
 * Iron golems
 * Endermen
 * Striders, when ridden by the player
 * Llamas
 * Ravagers
 * Drowneds on land
 * Turtles

Flying mobs (ghasts, phantoms, etc.) and water mobs (except turtles) do not jump.
 * Fishes, guardians and elder guardians flop around when out of water; they do not jump.

Blocks
Some blocks are affected when being jumped on, or when jumping is performed near them. Some blocks may also hinder or assist in jumping.


 * Water or lava negates jumping of any kind while being submerged in it. However, if the player is above the surface of the liquid, holding the jump key and in tandem with moving up against a block, the player attempts to jump out of the liquid in an effort to land on the block being moving toward.
 * Pressing the jump key while submerged in liquid make the player ascend in it.
 * Fences and gates have vertical collision that are a block and a half tall, negating the ability for any mob to jump over it.
 * Ladders and vines can be climbed by holding the jump key while being close enough to them. Simply moving forward into them achieves the same effect.
 * Farmland reverts to a standard dirt block if an entity jumps and/or lands on it. This also causes any seeds and crops planted in the farmland to pop out. Entities do not need to jump for this to occur, as simply landing on farmland from a fall causes the same effect.
 * Turtle eggs can be broken by being jumped/landed on enough times.
 * A player sinks in soul sand by 2 pixels, although players are still able to jump on blocks.
 * Honey blocks greatly decrease the jump height of any entity standing on it.
 * Slime blocks bounce entities back up to the height proportional to the downward velocity of the falling entity. Holding the jump key while falling on a slime block causes the player to jump just at the moment of making contact with the slime block. This can be done without suffering any fall damage. Holding the key while landing on a slime block completely negates the bouncing.
 * Sculk sensors are able to detect many interactions and movements from entities. They cannot sense when an entity jumps, but can sense when one lands. Jumping and landing while sneaking is not detected by a sensor. Walking or landing on a wool block also nullifies the vibrations, so the sculk sensors don't pick up on it. Wool can also nullify vibrations that are between both the source of the disturbance and the sensor itself.
 * If the sculk sensor is connected to any type of redstone circuit, the vibration of an entity hitting the ground causes the sensor to output a redstone signal strength of 5.
 * Pointed dripstone (also known as a stalagmite) that's pointing upward hurts any player or mob that lands on it. Standing on a stalagmite and then jumping harms the entity repeatedly. The farther a fall before landing on a stalagmite, the more damage it does even more so than standard fall damage.

Trivia

 * Jumping was one of the first transportation mechanics added.
 * The longest possible distance a player can jump without effects is over 9 blocks, by sprint-jumping out of a 2-block-high ice corridor.
 * The longest possible distance a player can jump with obtainable effects in survival is over 11 blocks. by using Potion of leaping, Swiftness and Slow falling combined with soul speed III boots on soul sand.
 * The longest possible distance a player can jump without effect s or ice is 5 blocks by just sprinting.