A very nice post on the origins of writing in the Roman Empire:
Latin, the language of the Romans, was originally spoken only in the small region of Central Italy known as Latium. It might well have been displaced by geographically more widespread Italian tongues such as Oscan and Umbrian, but Roman conquests made it the received speech of the peninsula, and ultimately of most wealthy or educated people all over a vast empire.
Writing began in the 7th century BC, when the Latin alphabet was devised as an adaptation of the Greek letters used by the Romans Etruscan neighbours. The earliest known written Latin is on the Lapis Niger, an inscriped block of stone, found in the Forum Romanum, that probably dates from the early 6th century BC. There is no way of establishing how many Romans became literate, but written records, orders and transactions were vital to the efficient running of the Empire, while poems, plays, political and philosophical reflections, letters, prayers and graffiti provided outlets for vivid self-expression that often bring the Romans very close to us.
Commemorative inscriptions and some official decrees appeard on stone or bronze, but a variety of materials were available for other purposes. A wooden tablet with a coating of wax was particularly useful for temporary personal memoranda and school work; the metal or wooden stylus that scratched letters into the wax had a flat top that could be employed for corrections or to erase all the written content so that the tablet could be used again. However, occasion this unstable medium also seems to have served for quite important documents.