Essays can consist of a number of elements, including: literary criticism, political manifestos, learned arguments, observations of daily life, recollections, and reflections of the author. Almost all modern essays are written in prose, but works in verse have been dubbed essays (e.g. Alexander Pope's An Essay on Criticism and An Essay on Man). While brevity usually defines an essay, voluminous works like John Locke's An Essay Concerning Human Understanding and Thomas Malthus's An Essay on the Principle of Population are counterexamples. In some countries (e.g., the United States and Canada), essays have become a major part of formal education. Secondary students are taught structured essay formats to improve their writing skills, and admission essays are often used by universities in selecting applicants and, in the humanities and social sciences, as a way of assessing the performance of students during final exams.
The concept of an "essay" has been extended to other mediums beyond writing. A film essay is a movie that often incorporates documentary film making styles and which focuses more on the evolution of a theme or an idea. A photographic essay is an attempt to cover a topic with a linked series of photographs; it may or may not have an accompanying text or captions. n countries like the United States, essays have become a major part of a formal education in the form of free response questions. Secondary students in these countries are taught structured essay formats to improve their writing skills, and essays are often used by universities in these countries in selecting applicants (see admissions essay). In both secondary and tertiary education, essays are used to judge the mastery and comprehension of material. Students are asked to explain, comment on, or assess a topic of study in the form of an essay. During some courses, university students will often be required to complete one or more essays that are prepared over several weeks or months. In addition, in fields such as the humanities and social sciences, mid-term and end of term examinations often require students to write a short essay in two or three hours.
In these countries, so-called academic essays, which may also be called "papers", are usually more formal than literary ones. They may still allow the presentation of the writer's own views, but this is done in a logical and factual manner, with the use of the first person often discouraged. Longer academic essays (often with a word limit of between 2,000 and 5,000 words) are often more discursive. They sometimes begin with a short summary analysis of what has previously been written on a topic, which is often called a literature review.
Longer essays may also contain an introductory page in which words and phrases from the title are tightly defined. Most academic institutions will require that all substantial facts, quotations, and other porting material used in an essay be referenced in a