Objective
The goal of the campaign, fixed before anything is made.
Every campaign starts with a goal stated in one sentence. There are three that matter. Raise awareness, so people know the company exists. Raise acceptance, so people are comfortable with it being there. Produce want, so people would rather have this than the alternative.
A campaign aimed at all three at once reaches none of them. Choosing one tells you which audience to speak to, which channel carries it, and what the message has to do. It also tells you what to measure.
The objective is fixed first. Everything after traces back to it, and anything that cannot gets cut.