Who was Peter?
Peter was one of Jesus' closest disciples and one of the most prominent early church leaders in the Book of Acts. His name was originally "Simon," but Jesus renamed him "Cephas," or "Peter." His name means "rock" or "stone".
More than any other character besides Jesus, Peter's personality comes through in the gospels. He was enthusiastic, brash, and spoke before thinking. He was also devoted to Jesus. In Matthew, Mark and Luke, it is Peter who first confesses Jesus as the Christ. In the Gospel of John, Peter is the first to recognize that Jesus has the "words of eternal life."
In Jesus' greatest hour of need, having been arrested and tortured, Peter famously denied knowing Jesus three times. Peter wass outside waiting to see what would happen with Jesus and was asked three times if he knew Jesus. All three times, he vehemently denied knowing Jesus. These denials were why Jesus restored Peter.
Matthew, Mark and Luke don't tell us about Jesus restoring Peter but, the Gospel of John emphasizes the restoration of Peter. Peter's restoration takes place in the final scene of John's gospel.