When true, the bars extend from the center post to the east.
minecraft:connection_north
false
false true
When true, the bars extend from the center post to the north.
minecraft:connection_south
false
false true
When true, the bars extend from the center post to the south.
minecraft:connection_west
false
false true
When true, the bars extend from the center post to the west.
Videos
History
There is an associated page listing all historical changes related to the appearance and/or sounds associated with this block in further detail than below; see /Asset history.
Notch revealed two new screenshots of a stronghold (in two different brightness settings) where the bars can be clearly seen alongside other common stronghold blocks. The lighting differences have been explained a bit (though not necessarily completely correctly) by a user on the forums.
Iron bars now use the "prismatic" model shape glass panes now use. However, there are issues with mapping and plane rendering directions; this change was presumably unintended.
If iron bars are set to render as the block inside of a minecart via commands or map editing, they now appears as this (previously they would be entirely invisible).
Unlike in Java Edition, the perpendicular upper rims and lower rims intersect each other rather than being offset from each other, causing Z-fighting. The offset also appears to be greater than in other editions at this point.
Iron bars can be found in the Miscellaneous tab in the Creative inventory.
Issues relating to "Iron Bars" are maintained on the bug tracker. Issues should be reported and viewed there.
Trivia
In Java Edition, a 2×2 area made of iron bars can make a square-shaped hole big enough for the player and most mobs to fit through, but not rain, water, etc. that can be used as an easy entrance for an underwater house, and even an exit if pistons are used. Glass panes work in the same way.
If a sign or a painting is placed on iron bars, it appears to float in the air.
Despite apparently being thin enough to do so, iron bars do not let a ghast's explosion touch the block beneath them as long as the block is protected from other angles of the explosion affecting it.
If an iron bar is connected to a block and a rail is placed on the block, the top texture of the iron bar disappears.
While curing a zombie villager, iron bars placed nearby speed up the healing process. The same happens with beds, and both these things occur in the stereotypical prison cell.
Arrows cannot be shot through iron bars in Bedrock Edition.
Because iron bars are 1 block high, the player can normally jump over iron bars, unlike fences.