Can you tell me about language development in early childhood?

Language development: I tell my parents that a child should say 2 to 3 words at 15 months, 2 word sentences at 2-years-old, be 50% understandable at 2-years-old, 75% understandable at 3-years-old, and 100% understandable at 4-years-old. If not, ask for a speech evaluation. The earlier children with language delays or articulation disorders receive treatment, the faster they improve. Hope that helped.