It’s called amazon web services.

In short there’s 3 major cloud providers

Amazon Web Services

Google Cloud Platform

Microsoft Azure

All 3 basically do the same thing, real simplified version of it. it’s kind of a giant pool of server resources that are leased to you by demand. So say if you are netflix and have 100 million people watching the day a new series drops, but then only have 1 million watching tuesday night, they pay based on how much is currently being used, rather than having to set everything to handle peak, but be idle 90% of the time.

again yeah it’s expensive for most purposes… and one can argue how bad it is on the whole, but it is kind of what most companies have been using for a lot of things for the last 15 years.