We generally learn to communicate our thoughts orally on a basic level as infants when we first acquire or develop language. According to one theory, we do so by hearing the speech of adults and gradually learn to associate words with things and actions. As we grow older, our knowledge of language, especially of syntax and abstract expression, gradually increases, allowing us to communicate more complex thoughts. In school, we develop increasing sophisticated modes of communication and learn to write. Another type of communication is visual, through gesture and expression. These often are as or more important than words for communicating tone and nuance. These are learned through repeated social interactions and imitation.