All spontaneous processes move toward equilibrium. This state is the thermodynamic definition of a system at equilibrium. While there are exceptions, exothermic reactions usually take place spontaneously and endothermic reactions do not. The products of an exothermic reaction have less energy than the reactants, therefore the reaction occurs naturally to reach a lower state of energy. Since temperature and pressure affect enthalpy, you should be aware of two more reaction types.
Isothermal reactions take place at a constant temperature.
Isobaric reactions take place at a constant pressure. He has three Internet resources that explain these using simple terms, not complicated equations. You should explore at least one of these resources before continuing. The amount of change in each of these functions depends only on the beginning and the final states, not on the path followed during the change. Their value depends on the path by which a system gets from the initial state to the final state.