An essay is a literary composition, usually brief and in prose, which presents a subject from the viewpoint of the author. It is probably the most flexible of literary forms and therefore the most difficult to classify. Essays vary greatly in length, style, and content. They have been written on subjects as diverse as the meaning of doors (On Doors by Christopher Morley), the history of roast pig (A Dissertation on Roast Pig by Charles Lamb), and the value of friendship (Friendship by Ralph Waldo Emerson). An essayist writing about a familiar subject, such as G. K. Chesterton on A Piece of Chalk, generally treats it from an unusual standpoint that will provide his readers with new insights. Alexander Pope wrote his celebrated Essay on Man and Essay on Criticism in the form of poetry.
Essays are usually written as articles for newspapers or magazines and later may be collected in book form. Most well-known writers have composed them at one time or another, although few authors are essayists only. Many people who are not professional authors write essays, usually for school examinations or as assigned compositions.
Style is the most important element in essay writing. The essayist, unlike the writer of a formal treatise, does not attempt to give a comprehensive study of a subject. He may even relate personal feelings and experiences, particularly in a way that will please his audience. His work may seem casual in style, but it is generally a complete composition, resulting from careful and logical organization. A good essay usually instructs and stimulates as well as amuses its readers.