Burning paper is an exothermic reaction. When paper burns, it undergoes a chemical reaction in which it reacts with oxygen in the air to produce carbon dioxide, water, heat, and light. This reaction releases energy, which is why we observe flames and heat during the burning process.
In an exothermic reaction, the energy released is greater than the energy required to initiate the reaction. In the case of burning paper, the heat produced can be felt and is typically sufficient to ignite additional paper or surrounding materials. This contrast with endothermic reactions, which absorb energy from their surroundings, making the surroundings cooler. Therefore, because burning paper releases heat and energy, we classify it as an exothermic reaction.