The alphabet is the most highly developed, the most convenient and adaptable form of writing. It consists of a number of purely conventional signs or symbols called letters, each one denoting a single sound, at least theoretically. Alphabetic writing is now universally adopted by civilized peoples; its use is acquired in childhood with ease–it is obviously much easier to learn 22, 24 or 26 signs than, for example, 45,000, or 10,000, or even 3000 Chinese symbols. The alphabet may also be passed from one language to another without great difficulty. It is no longer an exclusive prerogative of the priestly or other privileged classes, as ancient ideographic scripts were. Education has become largely a matter of reading and writing and is possible for all.