https://www.pcgamer.com/steam-delivered-15-billion-gigabytes-of-data-in-2018/

You don't download Steam games over the internet. Not exactly. Over the past three years, Valve has been delivering its games and other data over a global private network it's been steadily building up, as it detailed in a 2018 year in review post today. "We partner with Internet backbone companies around the world to build this network, which connects directly with over 28,000 regional and local networks in 28 cities in 21 different countries," Valve writes. "This private network lets us deliver games and carry game, voice chat, and other data with high speeds and low latency to users in more than 229 countries."

What kind of speeds, exactly? Valve says its "edge network capacity" is now 12 Tbps (that's 12 million megabits per second). The "edge" here refers to the locations of servers users connect to. Cloudflare has a good breakdown: "An edge server often serves as the connection between separate networks. A primary purpose of a CDN edge server is to store content as close as possible to a requesting client machine, thereby reducing latency and improving page load times."