What is time?

From Aeon, on the nature of time: "The flow of time could still be real as part of our internal experience, just real in a different way from a proton or a galaxy. Is our experience of time's flow akin to watching a live play, where things occur in the moment but not before or after, a flickering in and out of existence around the 'now'? Or, is it like watching a movie, where all eternity is already in the can, and we are watching a discrete sequence of static images, fooled by our limited perceptual apparatus into thinking the action flows smoothly?"