“Old Testament” and “New Testament” are the two broad sections in many Christian Bibles. They are connected in Christian reading, but they are not two books or a simple before-and-after summary. Each section contains different kinds of writing, and the Old Testament’s table of contents differs among Christian traditions.
What the Old Testament contains
Christian Old Testaments include writings shared with the Jewish Tanakh, but the names and book groupings differ. Many Protestant editions contain the same books as the Tanakh, counted and arranged differently; Catholic and Orthodox traditions include additional texts, with the details varying among Orthodox churches and editions. Christian Old Testaments bring together narrative, law, poetry, wisdom writing, and prophetic books.
Many Protestant Bibles list 39 books. Catholic editions include additional books often called the Deuterocanonical books. Orthodox editions may include additional texts or organize material differently. These descriptions are broad orientation, not a full account of every community or edition. Check the table of contents of the Bible you are using.
What the New Testament contains
The New Testament has four Gospels, which present accounts of Jesus; Acts, which narrates the early Christian movement; letters addressed to communities and individuals; and Revelation, a work rich in apocalyptic imagery. In many common Christian editions, these are counted as 27 books.
Readers encounter several forms here too. A Gospel narrative is not structured like a letter. A letter may address a specific community and situation. Revelation uses symbolic imagery and should be read with attention to its literary form and historical setting.
Why the names can be confusing
“Old” does not mean that these writings are unimportant or obsolete. The phrase reflects Christian terminology for the two-part arrangement. Jewish readers do not generally describe their scriptures as the Christian Old Testament, and many Christians prefer to acknowledge that distinction when discussing the texts.
“Testament” is related to the language of covenant. Christian traditions explain the relationship between the two sections in different ways, but they read the New Testament in relation to the scriptures that precede it. A beginner can first learn the structure without settling every theological debate about that relationship.
How to use this distinction while reading
When you open a passage, check which part of the collection it comes from and what kind of writing it is. A psalm, a prophetic poem, a Gospel story, and a letter each have different cues. Then read the surrounding section and see how the passage fits its book.
For example, a reference in Isaiah belongs to a prophetic collection in the Old Testament; a reference in Romans belongs to a New Testament letter. The reference tells you where to look, but the passage and its context tell you more about what you are reading.
Why editions may not match
Different tables of contents are an important practical detail when you use a study guide, app, or printed edition. A book may appear in one edition and not another; chapter and verse numbering may also vary in some locations. Before deciding that a reference is missing, compare the edition and its contents page.
To understand the Bible as a whole library, read What is the Bible? A beginner’s guide. If you want a gentle first step, see How to start reading the Bible.