ANSWER: There were not twelve apostles but thirteen (13), as Matthias was chosen to take the place of Judas after he committed suicide. What were the apostles to do? These men were more than simply students. Jesus, with the help of God the Father, chose each one of the twelve for a very special purpose (Mark 3:13 - 19).
The twelve apostles were chosen to represent Jesus, the Savior of mankind, in lands far beyond Jerusalem. They were to travel and tell people about the wonderful promise God was giving to all men everywhere. This promise is that if people would believe on the Lord Jesus Christ, repent and be baptized, and turn their lives toward God, they would be saved. These twelve were ambassadors or emissaries for the Kingdom of God to the peoples of the world. After his resurrection Jesus gave his apostles their mission (Acts 1:8).
We have some information about a few of the apostles (disciples) and very little data on the majority of the twelve. Below is a brief synopsis of each of them, in the chronological order Jesus called them.
John is the brother of James (the Greater) and author of one of the four gospels. He also wrote three other New Testament books and the book of Revelation. He was banished to the island of Patmos by Roman Emperor Domitian in 95 A.D., where he wrote Revelation. He was released from exile by Emperor Nerva around 97 A.D. Lived to around 100 A.D. Is believed to be the only one of the original twelve disciples who did not die a violent death.
Andrew, one of the first two of the twelve apostles Christ called, was a fisherman by trade. He was the brother of Simon Peter and lived in Bethsaida when Jesus called him. According to Foxe's Book of Martyrs preached the gospel to many Asiatic nations and was crucified in Edessa.
Peter was originally named Simon and renamed Peter by Jesus. A married fisherman from Bethsaida who was the third of twelve disciples Jesus called (John 1:40 - 42). He walked on water with Jesus (Matthew 14) and also denied 3 times he knew him (Matthew 26). Was a witness to Jesus' transfiguration (Matthew 17). Raised a widow from the dead (Acts 9). Was rebuked by Apostle Paul for his hypocritical behavior (Galatians 2). Wrote 2 New Testament books. Died a martyr at the hands of Rome around 67 A.D.
Philip resided in Bethsaida where also Andrew and Peter lived. Was also considered an evangelist. The apostle Paul stayed at Philip's house on his way to Jerusalem (Acts 21:8 - 10). According to Foxe's, he labored diligently in Upper Asia and suffered martyrdom at Heliopolis in Phrygia.
Nathanael is also called Bartholomew. He was the fifth of the twelve apostles called to be a witnessed of Jesus' life and teachings. Not much is known about him.
James (the Greater) is brother of the apostle John, is also called 'James the Greater' to distinguish him from the other disciple named James (who is the son of Alpheus). Was a fisherman in partnership with Peter. Was with disciples Peter and John when Jesus was transfigured (Matthew 17:1). James was beheaded by King Herod Agrippa in 44 A.D., making him the first martyr of the twelve apostles.
Matthew, also called Levi, was born in Nazareth and is the last of the twelve apostles where information about his life is more commonly known. His occupation was a tax-collector. The gospel he wrote, in 35 A.D., was the very first book written for the New Testament. According to Foxe's, labored spreading the gospel in Parthia and Ethiopia. Suffered martyrdom.
The below five out of twelve apostles were called at roughly the same time.
James (the Less) is also called 'James the Less' to distinguish him from the other disciple named James (who is John's brother). According to Foxe's, at age 94, was beaten and stoned by the Jews.
Judas (Thaddaeus) is also called Lebbaeus or Thaddaeus. Brother of the disciples James the Less and Simon (the Canaanite).
Simon is also known as Simon the Canaanite or Simon the Zealot. Was brother of the disciples James the Less and Judas (not Iscariot). According to Foxe's, preached in Mauritania, Africa and Britain.
Thomas is also called Didymus. After Jesus' resurrection, when the other eleven of twelve disciples had seen him alive, he refused to believe Jesus was back from the dead until he literally saw and touched his wounds (Matthew 28:9 - 10, Luke 24:36 - 48). The term "doubting Thomas" comes from Thomas' disbelief in Jesus' literal resurrection. According to Foxe's, preached the gospel in Parthia and India.
Judas Iscariot, the last of the original twelve apostles before Matthias was needed, was a thief who was allowed to carry the group's money bag. Judas betrayed Jesus to the chief priests for thirty pieces of silver. After his betrayal the remorse of his sin leads him to commit suicide. After his death the remaining apostles (disciples) must choose someone to take his place.