What is the use case of noop [:] in bash?

Question

I searched for noop in bash (:), but was not able to find any good information. What is the exact purpose or use case of this operator?

I tried following and it\'s w

Answer 1

I've also used in it scripts to define default variables.

: ${VARIABLE1:=my_default_value}
: ${VARIABLE2:=other_default_value}
call-my-script ${VARIABLE1} ${VARIABLE2}