Glass Pane

Glass Panes are transparent blocks which can be used as an alternative to glass blocks.

Obtaining
Glass panes can only be obtained by mining them using a tool enchanted with Silk Touch, otherwise they drop nothing.

Natural generation
Glass panes generate naturally as windows in Villages.

Usage
Glass panes are much more efficient than glass, as they can make windows of 267% the area of glass blocks, because only 6 glass blocks are required to make 16 glass panes.

Glass panes, along with iron bars, can be used in wireless redstone setups due to a block update glitch.

Placement
Before snapshot 15w31a, if placed without anything on the sides, they will appear in the shape of a from the top, but when something is placed on the sides, it will become flat or turn into a  shape or a  shape depending on the items surrounding it. But with the release of 15w31a, glass panes without connecting blocks or other panes are 2x2 pixels, as with their stained counterparts. The collision box is identical to the shape of the pane, allowing both items and players to fit through 2x2 glass pane holes.

Glass panes are never horizontal.

Glass panes may have an added feature in 1.9, where if they do not connect to other blocks, they have the apperancee of vertical rods.

Trivia

 * If two glass panes are placed with one empty space in between, a spider (which is 2 blocks wide) can still fit through.
 * Glass panes are called "thinGlass" in the game's code, but all glass pane texture files within minecraft.jar begin with the prefix "glass_pane" (e.g. "glass_pane_top.png").