Saucer separation was an emergency maneuver performed on some Federation starships involving the complete disconnection of the primary hull and the secondary hull. During the 23rd century, separation was a one-time only event used only in a catastrophic emergency; the two sections could not reconnect easily following a separation.
In the 24th century, some starship classes were designed to routinely separate into one or more components. The procedure itself became more common and tactical, as well as emergency, uses became standard procedure. By this period, separation technology had advanced sufficiently to be performed at warp speeds. The procedure was extremely risky, with no margin for error; partially due to this, a high-warp separation was never attempted prior to 2364.