In the Roman Catholic Church today would be called the Veneration of the Precious Chains of the Holy and All-Glorious Apostle Peter—commemorating both the chains which Saint Luke says miraculously fell from him (Acts 12:1-11), and the chains which he was held before his marytydom by Nero. The Anglican Church also honors Blessed Peter today, but with a different name - The Confession of Saint Peter.
In Saint Matthew's gospel, Jesus asks Peter "Who do you say that I am?" After telling who others say, Simon Peter finally answered, "You are the Messiah, the Son of the living God." And Jesus answered him, "Blessed are you, Simon son of Jonah! For flesh and blood has not revealed this to you, but my Father in heaven. And I tell you, you are Peter, and on this rock I will build my church, and the gates of Hades will not prevail against it. I will give you the keys of the kingdom of heaven." (In art we often see Saint Peter with keys).
According to tradition, Saint Peter was the first pope, but in reality, the monarchical episcopate of a single bishop ruling over a diocese doesn't seem to have developed until the second century. In the Apostle's days the Roman church was controlled by a body of presbyter-bishops who worked together. But that's another story for another time.
Today being a Sunday, most will transfer this observance to tomorrow when we will be doing many things, so I wanted to mention it today. Saint Peter, generally said to be first among the Apostles and an important figure for Christians.