Several leading tech companies are making big bets on cloud computing services, but with Amazon taking the lead, some analysts are wondering if other companies can match Amazon’s offerings.

In addition to Amazon, Microsoft and Google are leading the way in cloud developments, according to Entrepreneur. All of the companies have “hyperscaled” their cloud-based businesses, by constructing massive data centers that enable large and efficient storage and computing capacity.

The three companies also rent out their data centers’ capacity to developers worldwide, who can get virtually unlimited computing power with the swipe of a credit card. This allows virtually anyone to run software at large scale and high performance without needing to create and maintain a massive data center.

The companies all offer “infrastructure as a service” (IaaS) features, the most basic cloud service that allows users to establish virtual servers in the host company’s data center. They also offer another service called “platform as a service” (PaaS), which give developers the tools and resources they need to build applications without concern for the servers which they’re using.

A third layer is called “software as a service,” but is not typically considered part of cloud computing services. This refers to the use of cloud-enabled applications like Google at Work or Microsoft Office 365.

By attracting more customers, cloud service providers can add additional servers and computing power, thus enabling the company to serve more customers with improved services. Amazon calls this process the “virtuous cycle.” The company began experimenting with cloud services before most others, in 2006, and today takes in at least $7 billion in cloud service revenues. The services are forecast to bring in as much as $50 billion by 2020.

In the beginning, Amazon’s offerings primarily served smaller developers, but today companies like Netflix, Airbnb and even the Central Intelligence Agency use Amazon for their large businesses.