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.

Pistons
When pushed by a piston, entities on its top surface and adjacent blocks move with it. Mobs are not launched high in the air if a piston pushes them up, unlike the slime block's behavior.

Slowing down entities
Honey blocks slow down entities walking on top of them and prevent them from jumping. Players, who can ordinarily jump about $1 1/4$ blocks high, can only jump about $3/16$ blocks high on honey. They can more easily step up onto other blocks than jump up onto them.

Sliding
Entities attaching to 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.

Falling
As with hay bales, falling onto a honey block reduces the fall damage by 80%, i.e. the player or mob takes 20% of the normal fall damage.

Bees
When placed near beehives or bee nests, bees will occasionally fly close and attach to it for a few seconds, resembling an action of "eating honey". When doing this, a bee stops flattering wings and firmly attaches its face to a honey block.

This is regardless if there is any flower around.

Trivia

 * Honey blocks are not full blocks, they are 14*14 pixels on each side. Small-enough entities (like arrows) are free to move through the gap between honey blocks.
 * Only when entities are partially “in” the honey block 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.
 * They slow down players regardless of their movement (flying with elytra, swimming, etc).
 * Its bottom surface doesn’t affect entities.