Ammonium nitrate (NH₄NO₃) is a white, crystalline solid that is widely used as a nitrogen-based fertilizer. It is also used in explosives and as a component in solid rocket propellants.

Ammonium nitrate is produced by the reaction of ammonia with nitric acid. It is a stable compound, but it can decompose explosively when it is heated or subjected to shock or friction.

The explosion in Beirut was caused by a large amount of ammonium nitrate that was stored in a warehouse at the port. The ammonium nitrate was ignited by a fire, which caused it to decompose explosively. The explosion caused widespread damage to the port and surrounding areas.

Ammonium nitrate is a hazardous material, and it must be stored and handled properly to prevent accidents.