Which mode of voice communication is most commonly used on the HF amateur bands?

Single sideband (SSB) is by far the most commonly used voice mode on the High Frequency (HF) amateur bands. Its popularity stems from its excellent balance of bandwidth efficiency and effective range, making it ideal for the crowded and variable conditions of HF propagation. Frequency modulation (FM) is primarily used on VHF and UHF bands where bandwidth is less restricted, though it is used on a small portion of the 10-meter HF band. Double sideband (standard AM) is used occasionally by enthusiasts but is much less efficient, while single phase modulation is simply a distractor.