Tell me how to use it? why is it necessary?
Tradition, mostly...time was, most extended families only ever got ALL their members together in one place for weddings and funerals. The tradition of guestbooks, registries, even "autograph books" where people would collect their friends' signatures---- all of that comes from a time when not everyone owned a camera--- the only record of who people were and what they did, was the written word. Keeping records of family events was a way to keep up with family.
The registry wasn't complicated--- it was just a book for signatures; people would sign their names to 'register' their presence at the event.
A long time ago, people used to keep letters, write daily in their journals--likewise, they'd keep track of visitors and attendees of family reunions, weddings, and funerals. This was, for the common man, a way to keep up with history.
Don't you have an old school yearbook full of your friends' signatures and well-wishes? Same thing... same sentiment.
