Both :) the standard unit Of time is a dit. A dah is 3 dits long. 1 dit between each element (so s is ... But 5 dits long because its on, space, on, space, on). 3 dits between letters. 7 dits between words.

When people make the dits too long or the dahs too short (c vs y), or run characters together (ee or i?), it gets hard to copy correctly.