There are three levels of customer insight: Pains, JTBD and Zeitgeist.
To understand what an audience is, first we need to understand what it is not.
When you are at the beginning of your startup journey, your initial reflex might be to think of an audience in terms of their Demographics (Age, Gender, Profession, ...). Which makes sense if you are setting up a Google / Facebook Ad campaign.
However, demographics do not define an audience. They define a target group.
From the perspective of building audience-first, an audience is a group of people facing the same problem. Tackling the same needs. Chasing the same goals.
What they have in common is not their passport or resumé.
An audience is a group of people who share a journey.
What makes a journey? An end-goal or direction, a step-by-step route and progress, and challenges along the way.
Audiences gather. But a group of gathered people is not necessarily an audience.
Rather than focusing on where people gather, focus on why people gather (even if they don't do so currently), by applying the three levels of customer insight.
What critical pains are you looking to solve? What Jobs to be Done will you help complete? What Zeitgeist do you choose to enable, or entertain?