I can't really point to any one invention, but I would say that the way that cell phones have advanced has changed the course of our lives. Think about all the devices that your cell phone has taken the place of- we have no more pocket calculators, hardly anybody uses a watch except as a fashion statement, we can send emails, text messages, photographs, videos- point and shoot cameras are becoming extinct due to cell phone cameras!

So while mobile phones are older than fifteen years, the underlying technology has taken them far beyond mere telephones.