A digital mode capable of low signal-to-noise operation✓Bonne réponse
An eight-channel multiplex mode for FM repeaters
A digital slow-scan TV mode with forward error correction and automatic color compensation
Explication
FT8 uses fixed-length timed transmissions, a very small message format and strong error-correction coding, so the receiver can integrate over the whole transmission and decode signals that are well below the noise floor by ear. That is what makes it a low signal-to-noise mode rather than a voice or television mode.