Transfer of responsibility for providing air traffic control service.
That action whereby the responsibility for the separation of an aircraft is transferred from one controller to another.
Source: FAA JO 7110.65 (Air Traffic Control)
Description
The transfer of control (TOC) is effected at the transfer of control point. This is usually the point where the flight trajectory crosses the boundary between two adjacent areas of responsibility. This may be a published or a non-published point. An example of the latter is the transfer of control between vertically split sectors where the TOC point position may depend on the vertical speed of the aircraft.