Sorry about the formating:
The Earliest Extant Manuscripts
Fortunately, textual critics and paleographers have a large number of ancient manuscripts at their disposal, many of which have been found within the last century. Nearly the entire New Testament exists in manuscripts dated to before 300 AD. Other important manuscripts date to the fourth and fifth centuries.
The manuscripts dating from 100 to 300 AD are almost entirely papyrus fragments. These fragments are named with a "P" followed by a number. The vast majority of them were found in Egypt in the twentieth century, and are now kept in various museums and libraries throughout the world, including at Dublin, Ann Arbor, Cologny (Switzerland), the Vatican and Vienna.
The earliest manuscript of the New Testament was discovered about 50 years ago. P52 is a small papyrus fragment of the Gospel of John (18:31-33 on the front; 18:37-38 on the back), and it has been dated to about 125 AD. This makes it a very important little manuscript, because John has been almost unanimously held by scholars to be the latest of the four gospels. So if copies of John were in circulation by 125, the others must have been written considerably earlier. Moreover, the Gospel of John's greater theological development when compared with the other three gospels has led some scholars to conclude it was written as late as 120 or even 150 AD. The P52 fragment seems to make such late dates impossible. {4}
In addition to the early papyrus fragments, a large number of parchment manuscripts have been found that date from 300 AD onward. These are usually named for the place in which they were discovered and are abbreviated by a letter or sometimes a number. The manuscripts A/02 (Codex Alexandrinus), B/03 (Codex Vaticanus), and Sin./01 (Codex Sinaiticus) contain nearly complete sets of the New Testament. By comparing these to the earlier papyrus fragments, they have been shown to be quite reliable.
Codex Vaticanus (B), the earliest of the great parchment manuscripts at about 300 AD, has resided in the Vatican since the middle ages and remains there today. It is one of the most important manuscripts for textual criticism.
Codex Sinaiticus (Sin.) dates to about 350 AD. It was discovered in 1844 in a monastery on Mount Sinai by a Russian. After some resistance, he persuaded the resident monks to allow him to take it to St. Petersburg. On Christmas Eve, 1933, the Soviet government sold it to the British Museum for 100,000 pounds. It was put on permanent display in the British Library, where it still resides, along with other early biblical manuscripts. {5}
Codex Alexandrinus (A), dating to circa 450 AD, was transferred from the Christian library in Alexandria to the British Library in the seventeenth century, where it still resides today. The Catholic Encyclopedia details its history