Essay writing have become a major part of a formal education. Secondary students are taught structured essay formats to improve their writing skills, and 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 essays is a movie that often incorporates documentary filmmaking 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.