The word wedding comes from the Latin vote (plural of votum-promise) that the fact of making vows. With the confusion in the neutral Vulgar Latin lost its meaning and confused by v b.
A legend attaches a false etymology that in ancient Judea had the custom of killing a lamb for the barbecue in celebration or wedding anniversary. Over time, the kid was replaced by the female goat, the "wedding", the meat was much softer.
Killing the "wedding" was a sign that there feast. Because of this the name "wedding" has become synonymous with celebration, nowadays most spoken for weddings.
For each year, there is a material that represents a new stage. It is traditional in Western culture, celebrate with anniversary events related to marriage and the jubilee, other milestones of life.
This tradition comes from Germany, where it was customary that a settlement offer a silver crown to couples who did 25 years of marriage, and a gold to those who arrived at 50.
Over time, the number of symbols has increased and the tradition of offering these specific concerns directly with the stages of life, so the tradition has expanded to the rest of the world.
For each birthday, the gifts were of different materials, ranging from weakest to strongest, with the progression of the number of years, which symbolized the increasing strength of the relationship.