Well, delta g tells us the amount of free energy that is produced or used up when a chemical reaction takes place under certain conditions. So if a chemical reaction takes place and it releases gets free energy, that reaction will have a negative delta g value. And such a reaction is said to be spontaneous exergonic. And so this reaction releases useful energy that can be used to power other processes and reactions inside our cells and inside our body. Now, if the delta g is positive, what that means is that particular reaction will be endergonic, non spontaneous, and a positive delta g means we have to input energy for that reaction to actually take place. And in fact, inside our body, we can use exergonic reactions to produce energy and then that energy can be used to carry out undergonic reactions.