One item often overlooked by new home owners is changing locks or re-keying existing lock sets.  Upon close of escrow and taking possession of one's new home the first order of business is to make sure the home is secure and your family is safe. 

As anyone can imagine it is unlikely to know just how many of the prior owners keys are unaccounted for.  Keys left with workers, stashed under the doormats or over door jams, "hidden" around the house, etc.  While some might say that locks will only keep the honest people honest.  It is always better to be safe than sorry.  The safety of loved ones is surely priceless and protecting your family is simple and inexpensive.

For anyone in the greater Sacramento area I would suggest contacting Carl Woodard (aka - The Key Man) to have your changed or re-keyed when you move.  Carl and his team are specialists at re-keying residential lock sets. 

In writing this I found several interesting links to sites with the history of locks.  The first locks were made by the Egyptians approximately 4,000 years ago.  For more on the history of locks go to:  Schlage's History of Locks, History of Locks on About.com,  or Encyclopaedia of Locks and Builders Hardware.

Be safe!