This document discusses language acquisition in children. It notes that babies are programmed to distinguish between grammatical and ungrammatical language. Children go through stages of vocal development from cooing to babbling to single words. Around 12-18 months, children begin speaking single words that typically refer to objects. By combining words, children are able to convey simple meanings. Over time, children's linguistic productions become more complex as they test grammatical constructions. The document also discusses how children learn to form different types of questions at various stages. It notes factors that can influence second language acquisition in older learners.