The following definitions are designed to help writers understand the principles of creating an effective message.
For a message to be clear and effective, the writer must take a methodical approach to the writing process.
A clearly written document puts the reader first and is easy to read, understand and use. It is also logically organized, relevant to the reader and visually appealing.
But not every clear document is effective. A message is clear and effective only if it produces the desired result. Only the reader can tell whether a document is easy to read, understand and use.
Readable text allows the reader to instantly grasp every linguistic and typographical (layout) element after reading it only once. The layout helps the reader understand the content.
Understandable content allows the reader to grasp and process the information after reading it only once.
A usable document gets the message across: the reader can identify the purpose of the document (to inform, to persuade, etc.) or can use the information to carry out a specific task. In short, a document is usable if it reads well and contains a clear message.