is the reaction involved in sun for the production of heat and light fission or fusion or any else????????

nucler fusion

Yaar, i know it too how it occurs Explain

It is Fusion. The sun is composed mostly of Hydrogen.due to massive gravity of the sun, the hydrogen is compressed under grat force and nuclear fusion reaction starts. This reaction gives off helium gas. This gas then undergoes fusion and yields energy and lithium, this process goes on till iron and other metals.