But we’re still stuck with the term computer, and fundamentally, though it’s not at all obvious when we’re watching an animation on a web site, this is still what it does: compute anything that can be represented in an appropriate encoding, using binary representation, exceedingly fast, and with impressive accuracy. It is probably more accurate to talk of a computing system than a computer ­- the computing system is the combination of the physical computer and the conceptual program or software.

Computing systems extend the reach of our senses, our memories, our muscles, and even our very presence. Coupled with sensing instruments, they can perceive things on our behalf when we can't be there, or it's too dangerous for us, or we're otherwise engaged. Photographs of distant planets weren't sent back to Earth on film to be developed, but in binary signals that a computer on Earth could process and turn back into a visual object, such as a photograph of the rings of Saturn. They can extend our memory: keeping easily accessible millions of pieces of information. They can do things on our behalf where we're too large, too clumsy, too slow, not patient enough, too bored, when we have better things to do, or where (again) it might be dangerous for us to be.