The Vulgate is a Latin translation of the Bible, written in the late 4th century and start of the 5th, largely by the Dalmatia-born Eusebius Hieronymus (St. Jerome), who had been taught at Rome by the rhetoric teacher Aelius Donatus, otherwise known for advocating punctuation and as the author of a grammar and biography of Virgil.
Commissioned by Pope Damasus I in 382 to work on the four Gospels, Jerome's version of Holy Scripture became the standard Latin version, replacing many other less scholarly works. Although he was commissioned to work on the Gospels, he went further, translating most of the Septuagint, a Greek translation of the Hebrew that includes apocryphal works not included in the Hebrew Bibles. Jerome's work became known as the editio vulgata 'common edition' (a term also used for the Septuagint), whence Vulgate. (It might be worth noting that the term "Vulgar Latin" uses this same adjective for 'common.')
The four Gospels had been written in Greek, thanks to the spread of that language in the area conquered by Alexander the Great. The pan-Hellenic dialect spoken in the Hellenistic era (a term for the era following the death of Alexander in which Greek culture was dominant) is called Koine -- like a the Greek equivalent of Vulgar Latin -- and is distinguished, largely by simplification, from the earlier, Classical Attic Greek. Even the Jews living in areas with concentrations of Jews, like Syria, spoke this form of Greek. The Hellenistic world gave way to Roman dominance, but Koine continued in the East. Latin was the language of those living in the West. When Christianity became acceptable, the Greek Gospels were translated by various people into Latin for use in the West. As always, translation is not exact, but an art, based on skill and interpretation, so there were conflicting and inelegant Latin versions that it became Jerome's task to improve upon.
It is not known how much Jerome translated of the New Testament beyond the four Gospels.
For both Old and New Testaments, Jerome compared available Latin translations with the Greek. While the Gospels had been written in Greek, the Old Testament had been written in Hebrew. The Latin Old Testament translations Jerome worked with had been derived from the Septuagint. Later Jerome consulted the Hebrew, creating an entirely new translation of the Old Testament. Jerome's OT translation, however, didn't have the Seputagint's cachet.
Jerome did not translate the Apocrypha beyond Tobit and Judith, translated loosely from Aramaic. [Source: Dictionary of Greek and Roman Biography and Mythology.]
For more on the Vulgate, see the European History Guide's Vulgate Profile.
A. Codex Amiatinus, c. 700; Florence, Laurentian Library, MS. I.
B. Bigotianus, 8th~9th cent., Paris lat . 281 and 298.
C. Cavensis, 9th cent., Abbey of Cava dei Tirreni, near Salerno.
D. Dublinensis, 'the book of Armagh,' A.D. 812, Trin. Coll.
E. Egerton Gospels, 8th-9th cent., Brit. Mus. Egerton 609.
F. Fuldensis, c. 545, preserved at Fulda.
G. San-Germanensis, 9th cent. (in St. Matt. 'g'), Paris lat. 11553.
H. Hubertianus, 9th-10th cent., Brit . Mus. Add. 24142.
I. Ingolstadiensis, 7th cent., Munich, Univ. 29.
J. Foro-Juliensis, 6th~7th cent., at Cividale in Friuli; parts at Prague and Venice.
K. Karolinus, c. 840-76, Brit . Mus. Add. 10546.
L. Lichfeldensis,' Gospels of St. Chad,' 7th-8th cent., Lichfield Cath.
M. Mediolanensis, 6th cent., Bibl. Ambrosiana, C. 39, Inf.
O. Oxoniensis, 'Gospels of St . Augustine,' 7th cent., Bodl. 857 (Auct. D. 2.14).
P. Perusinus, 6th cent. (fragment), Perugia, Chapter Library.
Q. Kenanensis,1 Book of Kells,' 7th-8th cent., Trin. Coll., Dublin.
R. Rushworthianus, 'Gospels of McRegol,' before 820, Bodl. Auct. D. 2. 19.
S. Stonyhurstensis, 7th cent. (St. John only), Stonyhurst, near Blackburn.
T. Toletanus, l0th cent., Madrid, National Library.
U. Ultratrajectina fragmenta, 7th-8th cent., attached to the Utrecht Psalter, Univ. Libr. MS. eccl. 484.
V. Vallicellanus, 9th cent., Rome, Vallicella Library, B. 6.
W. William of Hales's Bible, A.D. 1294, Brit. Mus. Reg. I. B. xii.
X. Cantabrigiensis, 7th cent.,'Gospels of St. Augustine,' Corpus Christi Coll, Cambridge, 286.
Y. 'Ynsulae' Lindisfarnensis, 7th-8th cent., Brit. Mus. Cotton Nero D. iv.
Z. Harleianus, 6th~7th cent, Brit . Mus. Harl. 1775.
AA. Beneventanus, 8th~9th cent., Brit. Mus. Add. 5463.
BB. Dunelmensis, 7th-8th cent., Durham Chapter Library, A. ii. 16. 3>. Epternacensis, 9th cent., Paris lat. 9389.
CC. Theodulfianus, 9th cent., Paris lat. 9380.
DD. Martino-Turonensis, 8th cent., Tours Library, 22.
Burch. 'Gospels of St. Burchard,' 7th-8th cent., Würzburg Univ. Library, Mp. Th. f. 68.
Reg. Brit. Mus. Reg. i. B. vii, 7th-8th cent.