Wedding March

"Wedding March" (1842) is a piece of music for orchestra. Felix Mendelssohn wrote it in C major. It is one of the pieces he wrote for a performance of Shakespeare's play "A Midsummer Night's Dream". At weddings, somebody usually plays it on a pipe organ when the bride and groom leave the church. 
The march became popular for weddings when Victoria, The Princess Royal, married Prince Frederick William of Prussia on 25 January 1858 and chose the piece. The bride was the daughter of Queen Victoria. Queen Victoria loved Mendelssohn's music. 
Sometimes people call the "Bridal Chorus" from Richard Wagner's opera "Lohengrin" the Wedding March. This music usually plays when the bride goes into the church.