Written language is a way of recording language using any of various instruments and material, such as pen and paper, chisel and stone, or computers. The language itself is either spoken or signed, so written language develops as a way of representing what has been said. In many cultures, community languages are unwritten (such as Pirahã in Brazil).
There are several writing systems in use around the world, which record different elements of the languages they record. A syllabary, for example, assigns a symbol to each significant syllable of the language, while an alphabet records individual phonemes. Other systems involve symbols that usually incorporate meaning, such as Chinese characters. The decision over which system to use can be purely political or historical in nature, or there can be arguments that one system is better suited to the nature of a particular language. Over time, a system can change from representing one kind of linguistic unit to another - for example, the Latin alphabet emerged over the centuries via several other systems, ultimately descended from Egyptian hieroglyphs, which recorded meaning rather than anything like the present-day sounds of languages this alphabet has been adapted for, such as English.
When examining language that may be spoken or written, linguists generally consider that more fundamental insights can be gleaned into the nature of language by analysing natural, spontaneous speech, whereas the written word is considered at best an incomplete representation of a linguistic system. One reason for this is the fact that written language usually develops as a way to record spoken language rather than as a separate system. Another point is that children acquire their first language(s) through speech or signing, and never solely through writing; a focus on written language therefore ignores linguistic development prior to literacy. Another reason is that writing systems typically ignore many features of spoken language - for example, the English alphabet does not show stress (rebel, out of context, could be the verb or the noun), and the Japanese mora system does not record pitch accent.[1]