Glass

Glass is a block that first appeared in Creative version 0.0.18a_02. It has an almost completely transparent texture put on all six sides of the block. Glass uses a code that stops players from seeing other glass that is attached to the glass they are looking through in any parallel direction. Glass isn't generated anywhere on a natural map.

Glass is available for use in creative mode. It is often used for windows and other transparent parts of structures.

In the Survival mode test, glass blocks could be broken very quickly and would drop a glass block to pick up. The only way to obtain glass blocks was to place them on the map before the level was loaded in the Survival test client. In Indev, Infdev and Alpha, a block of glass could be crafted by smelting a block of Sand. When broken, the glass block cannot be re-obtained, so they must be placed wisely.

Sunlight can penetrate through glass, making glass the ideal material for creating a building that contains plants such as a greenhouse.

Torches, Railway Tracks and Ladders can not be placed on glass.

Swords can be used to break glass faster.

Glass blocks do not impede red wiring that turns a corner that shares an edge with the glass.

glitches
At the moment when water is above glass an infinite source cannot be created.

Trivia

 * Glass' texture is commonly changed to have the pixels in the middle of the block removed to provide a clearer view.
 * Notch plans to make lava turn sand into glass.

Glas