Per Tesla's own web site and description, Autopilot is an advanced driver assistance system that enhances safety and convenience behind the wheel. When used properly, Autopilot reduces your overall workload as a driver. 8 external cameras, a radar, 12 ultrasonic sensors and a powerful onboard computer provide an additional layer of safety to guide you on your journey. Cars built between September 2014 and October 2016 include one camera and less-powerful radar and ultrasonic sensors.
There are two Autopilot packages available for purchase: Autopilot and Full Self-Driving Capability.
Autopilot and Full Self-Driving Capability are intended for use with a fully attentive driver, who has their hands on the wheel and is prepared to take over at any moment. While these features are designed to become more capable over time, the currently enabled features do not make the vehicle autonomous.