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.