I am celebrating a prime birthday today, enjoying my 41 years on earth.  The importance of prime numbers is often underestimated.  Prime numbers serve as the privacy valves (and security valves) of the Internet.  A prime number is a natural number that has exactly two distinct natural number divisors: 1 and itself. Or to use a somewhat sloppier wording: a prime cannot be divided.

I am prime.  This implies that I cannot be divided, so stop the chain saws.  My attention will be divided as usual, and that argues for my attention not being prime. There are infinitely many prime numbers.

Public-key cryptography is what we wrap all things secret in, the ultimate secure wrapping of our on-line lifes.  Public key cryptography makes use of the difficulty of factoring large numbers into their prime factors, which is why we love our primes.  The fact that it is easy to do a calculation from components, but really really hard to go the other way, makes it possible to keep secrets (since the calculation of the crypto secrets cannot be reversed).  And girls keep secrets in the strangest ways.  Some of us use crypto.