Wikipedia: > In immediate mode, the scene (complete object model of the rendering primitives) is retained in the memory space of the client, instead of the gra

Wikipedia: > In immediate mode, the scene (complete object model of the rendering primitives) is retained in the memory space of the client, instead of the graphics library. This implies that in an immediate mode application, the lists of graphical objects to be rendered are kept by the client and are not saved by the graphics library API. The application must re-issue all drawing commands required to describe the entire scene each time a new frame is required, regardless of actual changes. React is simulating immediate mode by having the developer describe the full rendered result from the current data state. The developer / app code doesn't need to keep track of what changes need to be done to get the browser from its current state to the desired state, React does that for you. Retained mode is where the developer / app does have to concern itself with the current browser state and issue the desired updates themselves, like how everything was done in the jquery era and earlier.