The document summarizes language development from birth through three years old. It notes that infants begin with crying and cooing, then progress to babbling consonant sounds by 6 months. By their first birthday, infants say their first words, usually names. Exposure to language helps development, as toddlers learn 50-100 new words per month after 50 words are acquired. Their vocabularies grow from a few hundred words at age 2 to over 10,000 words by age 6.