Wedding Anniversaries were originally know by the number of years a couple had been married.
The traditional gift from a husband to his wife on their 1st anniversary was an eternity ring.
In medieval times it became popular in central Europe to celebrate the 25th and 50th Anniversaries with the husband crowning his wife with a wreath made of silver or gold. Although this practice has not continued we still use the terms 'Silver' and 'Golden' to describe the 25th and 50th anniversaries respectively. In Biblical times a 50th anniversary was called a jubilee and publicly announced with a trumpet fanfare.