Required reading refers to any work of textual media which is necessary to comprehend a specific subject, participate in discussion on that subject, or demonstrate competence and knowledge at that subject in an academic or professional environment.
It is typical for the curriculum of a school to feature lists of books which students are expected to read over specific intervals of time; these book lists are often moderately standardized within any geopolitical region, for students of a given age bracket. It is common for American high school students to read The Great Gatsby and Moby Dick, along with numerous works of Shakespeare. Standardized reading lists are created in an effort to maintain peer equivalency between students of the same age, regardless of location.
Required reading in a professional setting might include user manuals for a piece of technology, style guides for the editor of a publication, or a description of rules and protocol for interpersonal behaviour in a customer service environment.
Required reading can also be a component of entertainment: the prequel to a novel may be necessary to understand the events of that novel, and reading these books in the wrong order could create confusion for the reader.
Required reading is sometimes a phrase used in hyperbole by one person to convince another person to read a book that the latter will be likely to enjoy; in this instance, the only potential risk of not doing the "required" reading is loss of that enjoyment, rather than finding oneself unprepared for an academic or professional task.
The equivalent concept, where it pertains to visual media, is required viewing, and where it pertains to music and radio, is required listening.
Iron Noder 2015, 19/30