An author writes for a reason. That reason shapes every choice: word selection, sentence length, evidence, tone. The purpose might be to inform, to persuade, to entertain, or to express. A textbook informs. A campaign speech persuades. A thriller entertains. A private journal expresses. Most texts mix purposes, but one usually dominates.

Identifying purpose is a reading skill. Look at the title. Consider the audience. Examine the tone. A scientific paper uses neutral language and cites data. An opinion column uses emotional appeals and rhetorical questions. The same topic can be handled with different purposes. A article about climate change might inform in one publication and persuade in another.

Four main purposes

• Inform: present facts and explanations.
• Persuade: convince the reader to believe or act.
• Entertain: engage and amuse.
• Express: convey personal thoughts and feelings.

Purpose is not always stated. Sometimes the reader must infer it. A satirical essay entertains on the surface but persuades underneath. A memoir expresses personal experience but also informs about a time or place. The purpose determines how the reader should approach the text. Read an informative text for facts. Read a persuasive text for arguments. Read an entertaining text for pleasure. The author's purpose is the text's reason for existing. Without it, the words are just words.