Non-linear writing

A writing system is any conventional method of visually representing verbal communication. While both writing and speech are useful in conveying messages, writing differs in also being a reliable form of information storage and transfer. The processes of encoding and decoding writing systems involve shared understanding between writers and readers of the meaning behind the sets of characters that make up a script. Writing is usually recorded onto a durable medium, such as paper or electronic storage, although non-durable methods may also be used, such as writing on a computer display, in sand, or by skywriting.

The general attributes of writing systems can be placed into broad categories such as alphabets, syllabaries, or logographies. Any particular system can have attributes of more than one category. In the alphabetic category, there is a standard set of letters (basic written symbols or graphemes) of consonants and vowels that encode based on the general principle that the letters (or letter pair/groups) represent speech sounds. In a syllabary, each symbol correlates to a syllable or mora. In a logography, each character represents a word, morpheme, or other semantic units. Other categories include abjads, which differ from alphabets in that vowels are not indicated, and abugidas or alphasyllabaries, with each character representing a consonant–vowel pairing. Alphabets typically use a set of 20-to-35 symbols to fully express a language, whereas syllabaries can have 80-to-100, and logographies can have several hundreds of symbols.

...
Wikipedia