One server, one planet

Your online shop, shop.example, runs on one server in Virginia: the origin. Your code, your files and your database all live there.

Your customers don't. Every glowing dot is a request crossing an ocean and coming back, and the tag by each city is how long that round trip takes.

London hears back in about 85 ms. Sydney waits about 212 ms for the exact same file. Same server, same code. The only difference is distance.

The numbers in this lesson come from a simple model: great-circle distance, plus 30% for real cable routes, plus 8 ms for the last mile (home Wi-Fi to the ISP). Real pings wobble around them.