Writing is a type of communications of people who rely on the effort and practice. To write is to provide knowledge, ideas, feelings. A written requirement so that the recipient can read the message has been understood.
Writing is one of human communication that requires effort and discipline. The authors express their thoughts, feelings, needs to be in writing. So that the audience can understand.
Writing is one kind of human communication. We require effort and practice. Writing to show knowledge, thoughts, feelings, needs, is written "to the receivers can be read to understand.