The Boeing 737's MCP (Mode Control Panel) is a panel in the cockpit that controls the aircraft's autopilot system. The MCP allows pilots to adjust the aircraft's speed, altitude, course and other autopilot settings. Here are some key components and functions of the Boeing 737 MCP:

1. **Heading Selector:** Determines the direction of the flight. Pilots set the desired heading here, the system maintains this heading.
2. **Altitude Selector:** Used to set the altitude of the aircraft. It allows climbing or descending to a certain altitude.
3. **Speed Selector:** Controls the flight speed. Pilots can set a certain speed here and keep it at this speed during the flight.
4. **V/S (Vertical Speed) Selector:** Adjusts the vertical speed (climb or descent rate) of the flight.
5. **Autothrottle (Auto Throttle)**: Automatically controls and adjusts the speed of the aircraft. When the speed is set on the MCP, the autothrottle regulates the throttle to maintain that speed.
6. **LNAV (Lateral Navigation):** Automatically follows the direction next to the flight path. It performs this function using GPS or FMS (Flight Management System) data.
7. **VNAV (Vertical Navigation):** Manages the vertical profile of the flight path. It automatically makes climb and descent plans.
8. **AP (Autopilot) and FD (Flight Director) Buttons:** Provides autopilot on/off and flight director enable/disable functions.
The use of the MCP makes the flight more stable and safer because it automatically controls various aspects of the flight and minimises manual intervention by the pilots.