The incipit (pronounced IN-sip-it) of a text is the first few words used to identify it. In music, an incipit is the first few notes of a composition, serving the same purpose. The word "incipit" comes from Latin and means "it begins." The part at the end of a text is called the explicit, which in Latin means "it has been unfolded." This term refers to a papyrus scroll. The end of a text is also called "desinit," which means "it is finished."

Before titles were commonly used, texts were often identified by their incipits, such as in the example "Agnus Dei." During the medieval period in Europe, incipits were sometimes written in a different script or color than the rest of the text. Pages containing incipits were often decorated with pictures or designs. Although the word "incipit" is Latin, the practice of using the beginning of a text for identification existed long before classical times and was used in many parts of the world. Today, while not always called an incipit, the habit of referring to texts by their starting words is still common.

Historical examples

In the clay tablet archives of Sumer, catalogs of documents were created by making special tablets that listed the beginning parts of a group of tablets. These catalogs were used only by official scribes who had access to the archives. The size and detail of the clay tablets limited the length of the entries. An example from Lerner (1998):

Many books in the Hebrew Bible are named using their starting words in Hebrew. For example, the first book (Genesis) is called Bereshit, meaning "In the beginning…" Lamentations, which begins "How lonely sits the city…", is called Eykha, meaning "How." A well-known example is the "Shema" or "Shema Yisrael" in the Torah, which starts with "Hear O Israel…" – the opening words of a statement that expresses Judaism's belief in one God (found in Deuteronomy 6:4 and other places). The Lord's Prayer (found in Matthew 6:9–13), which begins in the King James Version with "Our Father which art in heaven, Hallowed be thy name…", is often called simply "Our Father."

The names of Parshiyot (sections of the Torah) are also based on starting words from the first two verses of each section. Each book is named after the first Parashah (section) within it.

Some Psalms are known by their starting words. For example, Psalm 51 (called Psalm 50 in the Septuagint version) is known in Western Christianity by its Latin starting phrase, Miserere, meaning "Have mercy."

In the Talmud, the chapters of the Gemara are titled using their first words. For example, the first chapter of Mesekhet Berachot ("Benedictions") is called Me-ematai ("From when"). This word appears at the top of every page in that chapter of the text.

In rabbinic tradition, the starting phrase is called the "dibur ha-matḥil," or "beginning phrase." It is a heading in published works that often quotes or summarizes a biblical or rabbinic passage to be discussed.

Many religious songs and prayers are known by their opening words.

Sometimes, an entire book is named after its "dibur ha-matḥil." For example, the mystical and exegetical writings of the Chabad-Lubavitch rebbes, called "ma'amarim," are mostly named after the starting phrase of their first chapter.

The final book of the New Testament, the Book of Revelation, is often called the Apocalypse, named after the first word of its original Greek text, ἀποκάλυψις ("revelation"). This word has become closely linked to the book's theme of the End of Days.

Each chapter in the Quran, except the ninth, begins with the phrase Bismillah Al-Rahman Al-Rahim, meaning "In the name of God, the Most Compassionate, the Most Merciful."

In medieval manuscripts, incipits are often, but not always, written in red. They may appear before illustrations or decorated letters.

Traditionally, papal bulls and encyclicals, which are official documents from the Pope, are referred to by their Latin starting phrases.

Some parts of the Vedas, such as mantras and hymns, also follow this practice.

Modern uses of incipits

The practice of selecting a few words or a short phrase to appear on a book's spine and cover began slowly with the invention of printing. Later, the idea of a title page with a short title and subtitle appeared centuries after the first books were made, replacing earlier, longer titles.

Today, the use of standardized titles along with the International Standard Bibliographic Description (ISBD) has made the incipit unnecessary for organizing information in libraries.

However, incipits are still used to describe untitled poems, songs, and prayers, such as Gregorian chants, operatic arias, many prayers and hymns, and poems by Emily Dickinson. It is clear that these are incipits and not titles when the text stops in the middle of a sentence, such as in Shakespeare's sonnet 55: "Not marble, nor the gilded monuments."

Latin legal terms are often identified by their first few words, such as "habeas corpus," which is short for "habeas corpus ad subjiciendum" ("may you have the person to be subjected [to examination]"). These words are the most important part of a longer legal document.

Many word processors use the first few words of a document as a default file name, assuming that the incipit might match the intended title of the document.

The space-filling text known as "lorem ipsum" is named after its incipit.

Sometimes, incipits are used for humor, such as in the television series The Beiderbecke Affair and its sequels, where each episode is titled with the first words spoken in that episode, such as "What I don't understand is this…" and "Um…I know what you're thinking."

In music

Musical incipits are written using standard music notation. They usually show the first few measures of a piece, with the most important parts of the music written on one line of notation (examples on the right show both versions with one line and all parts together). Incipits are helpful in music because they can help people remember the piece better than just the title. These incipits are found in music catalogs and in the tables of contents of books that include many different pieces.

In choral music, sacred or secular songs from before the year 1900 were often given titles based on the incipit text. For example, parts of the Catholic Mass and Latin versions of Bible psalms used in religious services are always titled with the first word or words of the text. Protestant hymns from the 18th and 19th centuries are also traditionally named using an incipit.

In computer science

In computer science, long strings of characters are sometimes called incipits, especially when they are encryption keys or product keys. Examples of this include FCKGW, which is used by Windows XP, and 09 F9, which is used by Advanced Access Content System. In Git, objects are identified using the first few characters of their hash.