A classic is a book accepted as being exemplary or particularly noteworthy, usually of some chronological age since its original publications. What makes a book "classic" is a concern that has occurred to various authors ranging from Italo Calvino to Mark Twain and the related questions of "Why Read the Classics?" and "What Is a Classic?" have been essayed by authors from different genres and eras (including Calvino, T. S. Eliot, Charles Augustin Sainte-Beuve). The ability of a classic book to be reinterpreted, re-translated, abridged and parodied, to seemingly be renewed in the interests of generations of readers succeeding its creation, is a theme that is seen in the writings of literary critics including Michael Dirda, Ezra Pound, and Sainte-Beuve. These books can be published as a collection such as Great Books of the Western World, Modern Library, or Penguin Classics, debated, as in the Great American Novel, or presented as a list, such as Harold Bloom's list of books that constitute the Western canon. Although the term is often associated with the Western canon, it can be applied to works of literature from all traditions, such as the Chinese classics or the Indian Vedas. A book considered by some as of similar notoriety and impact but more recent are frequently called "modern classic" or "upcoming classic".

Many universities incorporate these readings into their curricula, such as "The Reading List" at St. John's College, Rutgers University, or Dharma Realm Buddhist University. The study of these classic texts both allows and encourages students to become familiar with some of the most revered authors throughout history. This is meant to equip students and newly found scholars with a plethora of resources to utilize throughout their studies and beyond.

In 1850, Charles Augustin Sainte-Beuve (1804–1869) stated his answer to the question "What is a Classic?" ("Qu'est-ce qu'un classique?"):

The idea of a classic implies something that has continuance and consistence, and which produces unity and tradition, fashions and transmits itself, and endures.... A true classic, as I should like to hear it defined, is an author who has enriched the human mind, increased its treasure, and caused it to advance a step; who has discovered some moral and not equivocal truth, or revealed some eternal passion in that heart where all seemed known and discovered; who has expressed his thought, observation, or invention, in no matter what form, only provided it be broad and great, refined and sensible, sane and beautiful in itself; who has spoken to all in his own peculiar style, a style which is found to be also that of the whole world, a style new without neologism, new and old, easily contemporary with all time.

In this same essay, Sainte-Beuve quoted Goethe (referring to the "classics" concept): "Ancient works are classical not because they are old, but because they are powerful, fresh, and healthy."

The concept of 'the classic' was a theme of T. S. Eliot's literary criticism as well. In The Sacred Wood he thought that one of the reasons "Dante is a classic, and Blake only a poet of genius" was because of "the concentration resulting from a framework of mythology and theology and philosophy". (In commenting about Eliot's influence, Professor Jan Gorak stated that "the idea of a canon has become intertwined with the idea of the classic, an idea that T.S. Eliot tried to revitalize for the 'modern experiment'".) In echoes of Sainte-Beuve, Eliot gave a speech to the Virgil Society concerning himself with the very same question of "What is a Classic?" In his opinion, there was only one author who was 'classic': "No modern language can hope to produce a classic, in the sense I have called Virgil a classic. Our classic, the classic of all Europe, is Virgil." In this instance, though, Eliot said that the word had different meanings in different surroundings and that his concern was with "one meaning in one context". He states his focus is to define only "one kind of art" and that it does not have to be "better...than another kind". His opening paragraph makes a clear distinction between his particular meaning of classic having Virgil as the classic of all literature and the alternate meaning of classic as "a standard author".

Literary figures from different eras have also weighed in on the matter. Alan Bennett, the modern English playwright and author, said that "Definition of a classic: a book everyone is assumed to have read and often thinks they have read themselves."^{[better source needed]} Mark Van Doren, the Columbia University professor and poet, is quoted by Jim Trelease (in his library-monograph Classic Picture Books All Children Should Experience) as saying that "A classic is any book that stays in print". And in his "Disappearance of Literature" speech given in 1900, Mark Twain said (referring to a learned academic's lofty opinion of Milton's Paradise Lost) that the work met the Professor's definition of a classic as "something that everybody wants to have read and nobody wants to read".

In 1920, Fannie M. Clark, a teacher at the Rozelle School in East Cleveland, Ohio, attempted to answer the question of what makes a book a "classic" in her article "Teaching Children to Choose" in The English Journal. Over the course of her essay, Clark considers the question of what makes a piece of literature a classic and why the idea of "the classics" is important to society as a whole. Clark says that "teachers of English have been so long trained in the 'classics' that these 'classics' have become to them very much like the Bible, for the safety of which the rise of modern science causes such unnecessary fears." She goes on to say that among the sources she consulted was a group of eighth-graders when she asked them the question: "What do you understand by the classics in literature?" Two of the answers Clark received were "Classics are books your fathers give you and you keep them to give to your children" and "Classics are those great pieces of literature considered worthy to be studied in English classes of high school or college". Calvino agrees with the Ohio educator when he states "Schools and universities ought to help us understand that no book that talks about a book says more than the book in question, but instead they do their level best to make us think the opposite." Clark and Calvino come to a similar conclusion that when a literary work is analyzed for what makes it 'classic', that in just the act of analysis or as Clark says "the anatomical dissection", the reader can end up destroying the unique pleasure that mere enjoyment a work of literature can hold.