What does the insert key do in macOS?

Question

This key is basically useless unless you need overtype mode. In Windows Command Prompt, pressing it toggles overtype. But, in macOS Terminal, it doesn't even work. How do I get the insert key to toggle overtype in Terminal, and does it have any other use cases in macOS?

Answer 1

It serves no purpose whatsoever and is not even present on Apple keyboards. macOS does not have an 'insert' mode.

It registers as Keycode 114 & is titled 'Help', but it has no default function on macOS.

Characters: 
Unicode:    63302 / 0xf746
Keys:       Help
Key Code:   114 / 0x72
Modifiers:  8388864 / 0x800100 

According to Overtype mode in Terminal.app you can switch to Vim keybindings, which will then enable an insert mode, though I've never tried this.