Oral language development occurs in stages from birth through age 4. Babies first coo and babble consonant-vowel sounds between 4-6 months. Around 8-10 months, babbling becomes more varied and complex, resembling adult speech. From 1 year, children use single words and invented words. Between ages 2-3, they speak in short telegraphic phrases. By ages 3-4, most children are moderately fluent using oral language for communication. The development is facilitated through interactions with caregivers and peers in language-rich environments.