Throw a ball in the air and gravity pulls it straight back down. Not everything moves like this when gravity acts on it. Most objects are not nice, neat shapes like balls. That means gravity acts on them in more complex ways. Even so, all objects behave as though their mass (the stuff they're made from) is concentrated at a point called their center of gravity. A simple object like a ball has its center of gravity in a very obvious place: right at its center. But in a more complex object, like your body, the center of gravity is slightly higher than your waist because there's more weight in the top half of your body than in the bottom half.
Centers of Gravity (CG) are physical or moral entities that are the primary
components of physical or moral strength, power and resistance. They don’t just
contribute to strength; they ARE the strength. They offer resistance. They strike
effective (or heavy) physical or moral blows. At the strategic level, they are usually
leaders and populations determined to prevail. At operational and tactical levels they are
almost invariably specific military forces.