Student or Learner
Which one is correct :-
"Fill IN / OUT / UP the form."
fill in the form <grammatical>
fill out the form <grammatical>
fill up the form <ungrammatical>
The difference between "fill in" and "fill out" is this. "in" tends to refer to the boxes on the form, whereas "out" tends to refer to lines on forms. It's not a hard and fast rule, though. Speakers use either "in" or "out". Choose the one you like.