Thermal
Thermal flying can be done in any type of rc soaring. It is simply using rising, warm air to propel your rc glider aloft. Planes can be launched from flat field or slopes, by hand, high-start, aero-tow or winch and so represent the most diverse part of rc sailplane flying.
For the purposes of competition it is typically Thermal Duration of TD flying that is being discussed and there are several disciplines in the TD arena that can make up a contest but most in the US have in common some form of winch launch to altitude, a set duration time for the flight and a precision landing task.