Why does the groom stand on the right?

The tradition of the Bride on the left and the Groom on the right stems from a time long ago when marriages were "marriages by capture". That meant the groom needed his right arm free to draw his sword and protect his bounty i.e. his new bride.

A lot of the traditions that we hold to even today in modern weddings stem from a time when weddings were very different. I for one am certainly glad that the times have changed.