A range of small, circular connectors with a myriad of uses.
All are vile to solder, have poor strain relief and are the work of Satan. The Preh type have a locking ring that is probably the only redeeming feature of the range.
One rectangular and one round pin, was common in domestic HiFi as a speaker connector.
Used in Audio.
Zero 88 etc convention: pins 1 to 6 are channels 1 to 6, pin 7 is desk supply, pin 8 is ground.
Pulsar convention: pin 1 is desk supply, pin 2 is ground, pins 3 to 8 are channels 1 to 6.
The 4-pin version is used for for s-video, the 6-pin version is used for PS/2 mice and keyboards (coloured green for mouse and purple for keyboard).