Usually, a writer has one of four main purposes in mind when writing:
to narrate, or tell a story
to describe someone or something
to explain or inform
to persuade
An author might write a narrative for the purpose of telling family history or relating experiences of traveling. Or a writer might want to describe something, such as a new invention, restaurant, or fashion trend. The author of a biography is writing to inform; so, too, are writers of “how-to” articles, such as how to file your taxes. Political speeches, advertisements, and editorials are written to persuade.
A writer may also have more than one purpose — narrating a family history and, at the same time, describing a hometown, for example. You can often determine an author’s purpose by identifying the subject of a written piece and by paying close attention to the tone of the author’s words.
As you read, ask yourself, “What response is the writer expecting from the reader?”