The New Testament (Koine Greek: Ἡ Καινὴ Διαθήκη, Hē Kainḕ Diathḗkē) is the second major part of the Christian biblical canon, the first part being the Old Testament. Although Christians hold different views than do Jews about the Old Testament—that is, the Hebrew Scriptures—Christians regard both the Old and New Testaments together as sacred scripture. The contents of the New Testament deal explicitly with first century Christianity. Therefore, the New Testament (in whole or in part) has frequently accompanied the spread of Christianity around the world. It reflects and serves as a source for Christian theology. Both extended readings and phrases directly from the New Testament are also incorporated (along with readings from the Old Testament) into the various Christian liturgies. The New Testament has influenced not only religious, philosophical, and political movements in Christendom, but also has left an indelible mark on its literature, art, and music.

The New Testament is an anthology, a collection of Christian works written in the common Greek language of the first century, at different times by various writers, who were early Jewish disciples of Jesus of Nazareth. In almost all Christian traditions today, the New Testament consists of 27 books. The original texts were written in the first and perhaps the second centuries of the Christian Era, generally believed to be in Koine Greek, which was the common language of the Eastern Mediterranean from the Conquests of Alexander the Great (335–323 BC) until the evolution of Byzantine Greek (c. 600). All of the works which would eventually be incorporated into the New Testament would seem to have been written no later than around AD 150.