Pachelbel's Canon (also known as Canon in D major or just Canon in D) is the most famous piece of music by Johann Pachelbel. It was written in or around the time period of 1680, as a piece of chamber music for three violins and basso continuo, but it has been arranged for many other instruments since then. It is well known for its chord progression.
Pachelbel's Canon is often played at weddings.
This is Pachelbel's Canon played on a piano: