The ways in which spoken languages use sounds to construct meaning is studied in phonology. The study of how humans produce and perceive vocal sounds is called phonetics. In spoken language meaning is constructed when sounds become part of a system in which some sounds can contribute to expressing meaning and others do not. In any given language only a limited number of the many distinct sounds that can be created by the human vocal apparatus contribute to constructing meaning

Sounds as part of a linguistic system are called phonemes. All spoken languages have phonemes of at least two different categories: vowels and consonants that can be combined into forming syllables. Apart from segments such as consonants and vowels, some languages also use sound in other ways to convey meaning. Many languages, for example, use stress, pitch, duration and tone to distinguish meaning. Because these phenomena operate outside of the level of single segments they are called suprasegmental.

Writing systems represent the sounds of human speech using visual symbols. The Latin alphabet (and those on which it is based or that have been derived from it) is based on the representation of single sounds, so that words are constructed from letters that generally denote a single consonant or vowel in the structure of the word. In syllabic scripts, such as the Inuktitut syllabary, each sign represents a whole syllable In logographic scripts each sign represents an entire word. Because all languages have a very large number of words, no purely logographic scripts are known to exist. In order to represent the sounds of the world’s languages in writing, linguists have developed an International Phonetic Alphabet, designed to represent all of the discrete sounds that are known to contribute to meaning in human languages.