Photography, cinema and video not only record the way things look and move: they also record time. Take a photograph of a busy street. You have frozen a moment in time. Nothing in the picture will ever be the same again. Take a second photograph. Compare the two. They reveal how everything has moved and the time taken to do so. By taking pictures of the same scene over a period, you discover the rhythm of human and vehicle movement, how buildings change, the shifting patterns of night and day. Time is compressed, making its effects more apparent. Conversely, when a sequence of pictures is taken very rapidly, time is expanded. Events that happen too fast to see with the naked eye, such as explosions or the workings of machinery, are revealed. By using such methods, we increase our understanding of the physical world. We can also utilise them to create illusions, worlds of the imagination.