What React Component Instances Are and How They Work Under the Hood

React component instances are internal objects React creates each time a component is rendered in an application. Each instance stores contextual data specific to that component, including its state, props, children, and references to its DOM nodes. State hooks and props are tied directly to a specific instance's isolated memory, meaning each rendered copy of a component maintains its own independent data. When a component is unmounted through conditional rendering, React destroys its instance entirely, permanently discarding any stored state. Understanding instances helps developers grasp how React manages component lifecycles, updates, and memory behind the scenes.