There is a lot of domain crossover, and perhaps one day the related things will get merged and cleaned up.
Video also does audio. Some solutions also do desktop streaming.
TODO - do I have items/tags around here somewhere?
Some video streaming solutions can do this (e.g. Skype). Some of these also do audio.
- Audio-only streaming software
VoIP is about telephones.
These days, this functionality is built into most if not all audio or video solutions.
- Instant messengers is about text.
- Some websites have text chat built-in.