Although a number of melodies may be suitable music for weddings, there are two in particular from the world of classical music which are most frequently played. One is the Wedding March by Mendelssohn, and the other is this Bridal Chorus by Richard Wagner. This is associated with weddings because it is used in his opera Lohengrin at the marriage between the title character and Elsa. This is a simplified arrangement for piano.
The audio controls below allow you to play the mp3 version of Wagner's Bridal Chorus from Lohengrin for piano or you can download the MP3 file. You can also download the midi version of Wagner's Bridal Chorus from Lohengrin for piano.
The image below is the first page of the sheet music, and here you can download the full sheet music for Wagner's Bridal Chorus from Lohengrin for piano in PDF format.