Errors of growth, also known as overregulation, occur when a child learning a language incorrectly applies a general rule to all words. In English, adding the suffix "ed" to a verb, generally puts it into past tense; however, there are exceptions (such as with the verb to go). Babbling also occurs in language development, but it is spontaneous nonsense syllables that are a precursor to language. Phonology has to do with the basic building blocks of words such as letters. Pragmatics is the most complex component of language that has to do with the efficient use of language such as tone.