Even if you know that typical viewers will include readers with almost no background knowledge about your topic, you still need to decide what's most important to present on your poster and every bit of information about the audience will help you plan your poster. If you're writing a poster for a career fair, for instance, knowing that it will be held at a high school or at a college will make a difference in your probable audience. If you were describing actuarial science for a high school career fair, you'd need to explain just what actuaries do as well as the job prospects for qualified actuaries. You'd certainly want to include the basic requirements that students will need in their first years of college, but you might decide not to detail the levels of testing that actuaries complete for full certification.
