The letters found in the New Testament are also known as the Epistles.
There are no books called "letters" (or epistles) in the Hebrew Old Testament. All books that are designated as "letters" are Greek, and found in the New Testament.
If you're referring to St. Paul's letters in the New Testament, they are called epistles.
The Epistles
None. There are, however, two epistles (letters) from Paul TO Timothy.
Paul was the main writer of letters (epistles) in the New Testament.
The term used is 'epistles'.
The "Epistles" are letters from an Apostle to church members in other locations.
Paul, Peter, John, James, and Jude all wrote epistles that formed part of the New Testament.
There are 21 epistles in the New Testament. Also, if you read Revelation chapters 1 - 3 you will notice 7 more epistles (letters) that truly should be included in the count, making it a total of 28. Most people don't think to include them as epistles but they are 7 letters going to 7 churches and the definition of "epistle" is a writing directed or sent to a person or group of people".
Paul wrote 14 books of the Bible, starting with Romans and continuing through Hebrews.
Epistles