Burning, or combustion, requires two components: a fuel and an oxidant. Oxygen is the most common oxidant--after all, lots of it is in the air we breathe, so it's always around. But for combustion to happen, you still need a fuel, and usually we say that the fuel is burning (not the oxidant).

So: no, oxygen does not burn. But other things burn (almost always) in the presence of oxygen, such as hydrogen gas, or carbon found in wood, coal, gasoline.

Oxygen combines with other chemicals; the resulting chemical reaction is what we call fire. Oxygen by itself cannot burn any more than fuel could burn without the oxygen.

No, oxygen does not burn but it is required for other materials to burn. This is because we define “burning” (also called combustion) as reacting with oxygen in a way that breaks apart the bonds in the original material and replaces them with stable oxygen bonds. This process releases a lot of heat.

In organic materials like wood and gasoline, burning breaking bonds between carbon and other atoms like hydrogen to form mostly carbon dioxide (CO₂) and water (H₂O). (When oxygen can’t get to the fire fast enough, the process is incomplete and forms soot, made of only Carbon.)

This means that if you created an electrical spark in a room filled with only hydrogen gas, it would not burn, because there is no oxygen for it to react with. Similarly, if you created a spark in a room filled only with oxygen, it also would not burn because there is no fuel for it to react with.

The oxygen does not need to be in the gaseous form that we breathe for something to burn, however. Solid oxidizers like nitrates (NO₃-), chlorates (ClO₃-), or perchlorates (NO₄-) can provide oxygen in a powder form – often used in fireworks.

There are other reactions that look like burning but are not. For example, the sun’s heat is caused by nuclear fusion (where small atoms come together to make larger atoms) and produces so much heat that the materials glow. So, the sun may look like a fireball in the sky but it’s not burning oxygen like a fire would.