The center of gravity is the balance point of a physical object or system. It helps determine how stable something is when it moves, tilts, or carries extra weight. A vehicle with a higher or shifted center of gravity is more likely to feel unstable, tip, or behave unexpectedly under stress.
In cybersecurity, the phrase is often used as an analogy for the most important dependency, asset, or control point in a system. Attackers may focus on a center of gravity such as identity infrastructure, a cloud control plane, a signing key, or a trusted update source because compromising it can affect many other components. Defenders use the same idea to find single points of failure, harden critical services, add redundancy, and segment trust so one compromise does not destabilize the whole environment.