Barrels are common environmental objects and hazards. Barrels are activated by damaging them, letting them fall or making them catch fire. Barrels can also be pushed around.
There are two standard types of barrels: oil barrels and red barrels. Red barrels explode very quickly upon activation. Grey barrels have a 1-second delay between activation and explosion.
There is also an acid barrel which leaves terrain-disintegrating acid upon destruction. These types of barrels are rare. They looked like a black barrel with a green shade.
The Propane tank can also be spawned instead of barrels.
Barrels are often part of a long chain reaction. Naturally, it is not advised to make one explode while standing or running next to it. On the other hand, exploiting the barrels for one's own advantage is very often possible.