When you watch a video, it feels like it appears by magic. It does not. That video lives on a powerful computer, maybe on the other side of the world, and it travels to you in pieces.

The pieces zoom through cables — real, actual cables. Some are buried under your street. The biggest ones lie on the bottom of the ocean, thick as a garden hose and thousands of miles long, carrying flashes of light that spell out messages. Ships laid them across the sea floor, and sharks have actually tried to bite them.

When the pieces reach your house, your wifi router turns them into invisible radio waves for the last few steps to your screen. All of that — across an ocean, under your street, through the air — happens faster than you can blink.

Next time a video loads slowly, be a little patient: it may have just swum across the entire ocean to reach you.