On a Mac, press and hold a character key and a list of accent characters will appear. There are also dead key combinations using the option key to enter special characters directly.
If you’re like me and wondered what a dead key is…
A dead key is a special kind of modifier key on a mechanical typewriter, or computer keyboard, that is typically used to attach a specific diacritic to a base letter.[1] The dead key does not generate a (complete) character by itself, but modifies the character generated by the key struck immediately after.
Depends on your computing platform.
I see another reply has already covered Linux.
On a Mac, press and hold a character key and a list of accent characters will appear. There are also dead key combinations using the option key to enter special characters directly.
If you’re like me and wondered what a dead key is…
—Wikipedia