From The Art and Popular Culture Encyclopedia
At the beginning of a composition stands the opening sentence. Considered "most important", the opening sentence needs to entice the reader and sets the subject, the tone and possibly the style for the whole work, although this does not have to be obvious. David Lodge describes the opening sentence as the "threshold" of the novel. The opening line is part or all of the opening sentence that may start the lead paragraph. For older texts the Latin term "incipit" (it begins) is in use for the very first words of the opening sentence.
As in speech, a personal document such as a letter starts with a salutation; this, however, tends not to be the case in documents, articles, essays, poetry, lyrics, and general works of fiction and nonfiction. In nonfiction, the opening sentence generally points the reader to the subject under discussion directly in a matter-of-fact style. In journalism, the opening line needs to stimulate the reader's interest already aroused by the headline. It is in fiction where the art of the opening sentence flourishes as authors have much liberty in the way they can cast the beginning; they need, however, to attract attention, arouse curiosity, and entice, lest they lose their audience.
Techniques to hold the reader's attention include keeping the opening sentence to the point, showing attitude, shocking, and being controversial. One of the most famous opening lines, "It was the best of times, it was the worst of times ...", starts a sentence of 118 words that draws the reader in by its contradiction; the first sentence of Yes even contains 477 words. "Call me Ishmael" is an example of a short opening sentence that grabs the reader immediately. Formulaic openings are generally eschewed, but expected in certain genres, thus "Once upon a time...".
Inspired by the opening, "It was a dark and stormy night...", the annual tongue-in-cheek Bulwer-Lytton Fiction Contest invites entrants to compose "the opening sentence of the worst of all possible novels", and its derivative, the Lyttle Lytton Contest, for its equivalent in brevity.