It's official: Amazon has the strongest cloud business

At long last, Amazon has finally revealed numbers for its cloud computing service, Amazon Web Services. $1.57 billion in the first quarter. This was around what most analysts had predicted - about $6 billion per year.

It's also profitable. It earned $265 million this quarter, putting it on track for $1 billion a year in profits.

This also gave concrete proof to what nearly everyone in the industry expected: Amazon is, by at least one measure, the biggest cloud computing infrastructure player of them all.

IBM wants to dispute that. Last week it told us, when you combine all the things it calls a cloud: on a trailing twelve-month basis its cloud revenue was $7.7 billion.

But it also clarified that its the things that it is selling "as-a-Service" is on track to do $3.8 billion. That's a more apples-to-apples comparison to the kind of cloud that Amazon sells.

IBM is well known for selling something called the hybrid cloud, which is when companies buy hardware and software the old-fashioned way, and install it in their data centers but set it up so that it can tap into IBM's cloud (hosted elsewhere) if they need more storage, or compute power or what-have-you.

IBM also does well in "private cloud" which is when companies remodel their data centers with hardware and software to mimic the big internet companies, which are are fast and efficient.

Microsoft's cloud services are at $6.3 billion a year. Microsoft on Thursday also revealed its latest cloud computing numbers - its cloud computing business is on track to pull revenues of $6.3 billion this year.

But this also isn't quite apples to apples. Microsoft includes its software-as-a-service apps, Office 365 and Dynamics CRM (a Salesforce competitor) in its cloud revenue. Its cloud infrastructure service, Azure, competes most directly against AWS. And it's some smaller portion of that $6.3 billion total. One person has told Business Insider that Azure revenue is at $1 billion lifetime since its debut in 2011, but is accelerating quickly.

Google earns about $7 billion a year from all non-advertising businesses. Google is thought to be behind Amazon, Microsoft and IBM in this race (but catching up fast). Google also released earnings this afternoon, and it said that its "Other" segment, which includes all its enterprise apps and its nascent cloud computing business, had revenues of $1.75 billion this quarter, or $7 billion a year.

But once again, this includes all businesses at Google outside of advertising, so there's a lot more than cloud computing in there.

At stake is hundreds of billions of dollars in future revenue as companies stop buying all their own tech and start renting more of it from cloud providers.

Disclosure: Jeff Bezos is an investor in Business Insider through hispersonal investment company Bezos Expeditions.