> What is the significance of an anniversary?
>
> So a year has passed! So what!
>
> The event took place. Whether it was one week ago or one month ago or one year ago or one hundred years ago....why is the anniversary important?

Anniversaries are obviously not necessary, but they are significant in the way that they:

A) Serve as an outlet to display (in a greater quantity than on an every-day basis) any devotion, adoration, gratitude, etc...

B) Serve as reminders for happy occasions that we like to keep in mind, as well as reminders of the not-so-happy occasions that we do not necessarily want to forget.

C) Are often just a celebration of life! And what's not to celebrate about that?

D) Give us an an excuse to eat cake.

The Other "Personally, I'm a big fan of cake" Matthew