Perceptual and language development are closely linked processes that occur rapidly in the first years of life. Perceptual milestones include visual acuity improving to adult levels by age 1 and the ability to crawl and walk allowing engagement with the environment. Language development moves from pre-production to using two-word phrases in toddlers to more complex sentences with vocabularies of thousands of words by ages 5-6. Critical periods exist where lack of appropriate stimulation can impact development of certain perceptions.