For the sake of this blog, we have defined the "Stages of Life" as: Infant = 0-1 year. Toddler = 2-4 yrs. Child = 5-12 yrs. Teen = 13-19 yrs. Adult = 20-39 yrs. Middle Age Adult = 40-59 yrs. Senior Adult = 60+. You can follow along with this blog series on the infographic below..