This is an old clip, but it's a good one. Years ago, Steve Jobs gave the perfect analogy to explain computers. He called it a "bicycle for the mind."
If you can't watch with the sound on, Jobs says that humans without bicycles are relatively inefficient creatures. But, we're tool builders, so we built the bicycle to make us as efficient as a condor.
Likewise, the computer is a tool we've build to enhance our brains.
Technology blogger Ben Thompson wrote about this recently. He said the mobile phone is the perfect tool for what Jobs was talking about.
"This is exactly what the iPhone and the smartphones that followed have done for people: instead of a computer being a destination, it's something that is always with us, ready to call up a map, or a restaurant recommendation, or simply fill time with a flapping bird," says Thompson. "To put it another way, mobile is a big deal not because we use computers more, but because a computer is with us in more places."