Communication skills develop sequentially from understanding to speaking, to reading, and finally to writing. Babies learn to convey their pleasure or discomfort through prespeech utterances almost as quickly as they are able to distinguish between states of satisfaction and distress. They enjoy listening to their own babble long before they learn to string phonemes into words and they are able to understand words spoken to them before they are able to talk. The nonverbal communication, the phoneme shaping, and the receptive understanding are stages of prespeech, each being a developmental precursor to the emergence of words. The tacit understanding of linguistic structure that toddlers demonstrate in their acquisition of speech is the foundation for the explicit grammar they will use much later when they learn to comprehend written discourse.