High Frequency Broadcasting (HF) (also known as Shortwave Broadcasting), is a radio service licensed by the Federal Communications Commission (FCC) to operate between 5,950 kHz and 26,100 kHz. This is an international broadcast service where transmissions are intended to be received by the general public in foreign countries. The rules applicable to this service are located in Part 73 Subpart F of the FCC Rules. Unlike other broadcasting services, HF broadcasters are authorized frequencies on a seasonal basis. Currently, two seasons exist: a Summer season and a Winter season. The adjustment of frequencies between seasons results mainly from changes in propagation conditions, altered programming needs, and objectionable interference situations.