There are actually a lot of digital modes that have been developed over the years.

• RadioTeleTYpe (RTTY)  🔗 Radioteletype (Wikipedia)
• AMTOR  🔗 AMTOR and PACTOR (G4AON)
• PACTOR  🔗 AMTOR and PACTOR (G4AON)
• Clover  🔗 Clover (ARRL)
• Frequency Shift Keying (FSK)
• Phase Shift Keying (PSK31)  🔗 PSK31 (ARRL)
• Facsimile (FAX)
• Slow Scan TeleVision (SSTV)
• Automatic Identification System (AIS)
• Continuous Wave (CW)
• WSPR  🔗 WSPR (ARRL)
• FT4, FT8