When they started, I understood them as a CDN - storing copies of your static(ish) bytes on lots of servers distributed globally. Happens to be that a globally

When they started, I understood them as a CDN - storing copies of your static(ish) bytes on lots of servers distributed globally. Happens to be that a globally distributed network of endpoints is also pretty great for absorbing DDOS attacks, so they started offering that too. And then I guess they parlayed that further into offering other T1/T2 level Internet services too. I don't use them for CDN / DDOS but I do use them for other things and I think they're great.