A.?CPS-3 is a longitudinal, prospective cohort study. That means we recruit and collect data from a large group of people, called a cohort, who are all cancer free at the start, making this a prospective study. The study is also a longitudinal type because we continue to collect data for many years, with participants responding to surveys and providing biological samples. Our goal is to better understand why and how certain people develop cancer while others remain cancer free.