Honey Block

Honey blocks are sticky blocks craftable from honey bottles.

Obtaining
Honey blocks can be broken instantly, regardless of held items.

Usage
Mobs avoid walking on honey blocks.

Unlike the slime block, the honey block does not carry a redstone signal because it is a transparent block.

Redstone
When being moved by a piston, entities on a honey block's top surface move with it. They are not launched in the direction of the push, as a slime block would do.

When a honey block is moved by a piston, it attempts to move all adjacent blocks in the same direction. A honey block can move any block a sticky piston can pull, except for glazed terracotta and slime blocks. The blocks that are moved may, in turn, push other blocks, as if they were being pushed by a piston. For example, a honey block sitting on the ground attempts to move the ground block underneath itself, which pushes additional ground blocks in the direction of motion.

When the adjacent block that is moved is also a honey block, that block also attempts to move all its adjacent blocks. For example, a 2×2×2 cube of honey blocks may be pushed or pulled as a unit by a single piston acting on any of the blocks in the cube.

A honey block adjacent to a block that cannot be moved by pistons ignores the immobile block. However, if an adjacent block could be moved but is prevented by the presence of an immobile block, the honey block is also prevented from moving. Liquids are an exception: they aren't moved, but neither do they stop a piston from pushing or pulling blocks into their space (usually destroying the liquid, and in a rare case displacing it through the piston). Honey blocks, unlike slime blocks, cannot have a redstone signal sent through them via a repeater or an observer, etc.

Honey blocks are not pulled by a non-sticky piston, nor are they moved if an adjacent (non-honey) block is moved by a piston.

The maximum of 12 blocks moved by a piston still applies. For example, a 2×2×3 of honey blocks may be pushed or pulled by a sticky piston as long as no other movable blocks are adjacent to it.

Honey blocks moved by pistons do not move entities that are touching the side or bottom of the block. Despite the fact that they are indeed touching the block, this behavior of not moving entities is considered completely intentional game design, despite being inconsistent with blocks.

Slowing down entities
Honey blocks slow down entities walking on top of them and prevent them from jumping. $$, players also slow down slightly if walking up against the side of it. Players, who can ordinarily jump about $1 1/4$ blocks high, can only jump about $3/16$ blocks high on honey; this is an 85% reduction. They can more easily step up onto other blocks than jump up onto them.

This effect applies even through other blocks on top of honey blocks as long as they are half-block or less in height - so the player cannot jump on carpets, bottom slabs or daylight detectors that are placed on honey blocks.

Sliding


Entities pressed against the sides of a honey block slide down at a slow speed and do not take fall damage, similar to going down a ladder but with a gradually decreasing horizontal momentum. This allows players to jump 2 blocks further by holding on to the walls.

Falling
As with hay bales, falling onto a honey block reduces the fall damage by 80%, for example, if a player or mob falls from a height and would otherwise take damage, then if they land on a honey block they actually take  damage.

Bees
When a honey block is near bees and a beehive or bee nest, bees will occasionally fly close and attach to it for a few seconds, resembling an action of "eating honey". When doing this, the bee stops fluttering its wings, and firmly attaches its face to the honey block. This is regardless of whether any flowers are around.

Video
Here's a quick demostration, featured on Minecraft website.

Trivia

 * Honey blocks are not full blocks: despite taking up 16 pixels, the collision box is only 14*14*15 pixels.
 * The bottom face of the honey block is the same depth as a full block, though it is only 14*14 pixels.
 * Small entities such as arrows are free to move through the gap between honey blocks as they are under 2 pixels wide.
 * Only when entities are partially "in" the honey block (i.e., they are touching the 14 -pixel hitbox) can they slide down against it.
 * In real life, bees eat honey when the temperature is low and flowers are difficult to find. Otherwise, pollen is their primary food.
 * Honey blocks will slow down players regardless of their movement (flying with elytra, swimming, etc).
 * The bottom surface of the honey block does not slow down entities.
 * The slow on descending also stacks with the Slow Falling status effect.
 * The player cannot place some blocks on the honey block such as vines, ladders and torches.