standard enthalpies of formation

[Hailey Boehm 2H]

What exactly is standard enthalpy of formation? and why is it 0 when in the case of an element in it most stable form?

[Jonathan Zhao 4H]

The standard enthalpy of formation is the net change in enthalpy, or in simpler terms, the net change in heat, for one mole of a substance in standard state to be formed from its pure elements. A standard enthalpy of formation of 0 means that the substance is already in standard state.

[AdityaGuru1H]

basically it is the enthalpy required to form the product from reactants that are in their most stable state. Since the product is the most stable state the standard entalphy will be zero. It is a comparative value between the stable reactant and the product