How it was found
In June 1961, an Italian team was digging in an old Roman theatre at Caesarea, on the coast of Israel. Caesarea was where the Romans ran the region from.
They found a block of limestone that had been cut down and reused as a step. Carved on its face were four lines of Latin.
What it says
The stone is damaged, so parts are missing. Dark letters are still on the stone. Faded ones have been filled in.
What the Bible says
"Now in the fifteenth year of the reign of Tiberius Caesar, Pontius Pilate being governor of Judea..."
Luke 3:1 ยท Pilate also appears in Matthew 27, Mark 15 and John 18 to 19
See the match? Luke names the same emperor, the same man and the same job that the stone does. The difference is that the stone was carved while Pilate was alive, by Pilate himself.
Why this is a big deal
Before 1961, Pilate was known only from writings: the Gospels, the Jewish writers Josephus and Philo, and the Roman historian Tacitus. This stone is the earliest surviving record of him, and it comes from his own lifetime.
It also cleared up his title. The Roman historian Tacitus, writing decades later, called him "procurator". The stone says "prefect", which was the right title for that job at that time.