Firedamp is a flammable gas found in coal mines. It is actually the name given to a number of flammable gases, including methane. It is particularly commonly found in areas where the coal is bituminous.

Firedamp is explosive at a concentration of around 10%, and caused much loss of life in coal mines before the invention of the Davy lamp. Even after the safety lamps were brought into common use, firedamp explosions could still occur from sparks produced when coal contaminated with pyrites was struck with metal tools. The presence of coal dust in the air increased the risk of explosion with firedamp, and indeed could cause explosions itself.

The Tyneside coal mines in England had the deadly combination of bituminous coal contaminated with pyrites, and a great number of lives were lost in accidents due to firedamp explosions, including 102 dead at Wallsend in 1835 and 164 killed at Seaham in 1880. Rather than the Davy lamp, Tyneside miners used a similar safety lamp designed by George Stephenson.

Gases (other than air) in coal mines in England were collectively known as "damps". This comes from the German word Dampf (meaning "vapour"), and was probably introduced when German miners and mine engineers were brought to England in the seventeenth century to help in the development of deep mining.

Other damps included chokedamp (carbonic acid gas) and the insidiously lethal afterdamp – carbon monoxide produced following explosions of firedamp or coal dust. Synonyms may include whitedamp for firedamp and blackdamp for afterdamp.