Fence

Fences are wall blocks that cannot normally be jumped over.

Obtaining
Wood fences are broken most quickly with an axe, but will drop when broken with any tool. Nether brick fences require a pickaxe, mining it with anything else will drop nothing.

Natural generation
Oak fences spawn naturally:
 * As the uprights for the supports in abandoned mineshafts, where they are plentiful.
 * In villages, where they appear in tables, lamp posts, and even enclosures on roofs or behind buildings.
 * In library rooms of strongholds as railings and chandeliers. In the latter case, there are many torches attached to them.
 * On the "patios" and in the front window of witch huts.

Oak, birch and dark oak wood fences generate naturally in woodland mansions.

Nether brick fences can be found naturally in nether fortresses where they form window bars, balcony fencing, and gate-like structures.

Dark oak fences spawn as the supports in above-ground mineshafts.

Barrier
While fences appear to be a single block tall, and have a hitbox height of one block, their collision box (for entities) is 1.5 blocks tall, meaning most mobs cannot jump over them without the Jump Boost status effect. They are transparent to light and have visual gaps in the model.

A fence occupies the center space of blocks and automatically connects to any solid block that is placed next to it. Wood fences will connect to other wood fences, but will not connect to nether brick fences.

Since their hitbox is smaller than a single block, it will allow a player/mob in the block to breathe even when submerged.

Leads
Fences can be used to attach mobs with a lead.

Fuel
Wooden fences can be used as a fuel in furnaces, smelting 1.5 items per block.

Trivia

 * If a carpet is placed on top of a fence, a player can jump onto the carpet, while mobs will not (except rabbits).
 * Getting hit by someone else (or shooting yourself with a Punch enchanted bow while sprinting forwards) while in midair can cause the knockback to propel you over a fence you would not be able to jump over normally.
 * When 1.13 is released for Java Edition, water will be able to be placed on the same block on semi-transparent blocks, by a water bucket on that block.