The virtual assistant in iOS can do all kinds of stuff, of course. But here are the 16 things we think everyone should try at least once.
In most vertebrates and some molluscs, the eye works by allowing light to enter and project onto a light-sensitive panel of cells, known as the retina, at the rear of the eye. The cone cells (for colour) and the rod cells (for low-light contrasts) in the retina detect and convert light into neural signals for vision.
Your eye focuses this light into an image on the layer of the eye called the retina. The eyes receive light from many different directions and distances. To be seen, all this light must focus on the comparatively tiny area of the retina. This means the eyes have to bend light from different angles and directions.