Happy Birthday Google: Celebrate With All the Anniversary Doodles [PICS]

This month marks Google's 13th anniversary. The exact date Google celebrates this occasion has changed over the years, according to the company, "depending on when people feel like having cake."

However, in recent years Sept. 27 is the day the celebratory Google Doodle appears; since 2002 Google has put up a different doodle each year. To celebrate, we've taken a look back at every birthday doodle posted -- starting with today's.