When something burns , it react with the oxygen in the air .

sometimes ashes are formed . the ashes contains a new substance

The new substance in ashes are oxides

"Burning" is a chemical process in which a substance reacts rapidly with oxygen and releases heat and light, typically in the form of flames. This process is also known as combustion. It usually produces byproducts like carbon dioxide, water vapor, smoke, and other gases, depending on what is being burned.

There are two main types of burning:

Complete combustion – occurs when there is plenty of oxygen, producing carbon dioxide and water.

Incomplete combustion – occurs when there is limited oxygen, producing carbon monoxide, soot, and other pollutants.

Examples include burning wood, gasoline, or natural gas.