In the early days of the internet, if you wanted to launch an application, you had to buy or rent hardware. This was a physical server or a rack of servers, and you needed one server per application, so it was expensive. In 2001, VMware came out with virtualization—software that allowed users to run multiple applications on the same hardware. This meant you could split up a single box into multiple virtual boxes, each running its own environment and applications. The cost savings for businesses were tremendous.
Fast forward to 2006. Amazon popularized the concept of Infrastructure as a Service (IaaS) with Amazon Web Services and its Elastic Compute Cloud (EC2). You no longer had to buy your own hardware. You didn't even have to worry about running and managing virtual machines that run your applications. You were literally renting the computing environment and underlying infrastructure needed to run your services. You paid by the hour, like renting a conference room. This allowed companies to optimize resources to reduce costs and buy only as much computing power as they needed. It was revolutionary and led to an astounding decline in the cost of computing.
Three years after that, Heroku came up with the idea of Platform as a Service (PaaS). PaaS operated a layer above EC2 by removing administration of the virtual operating system. Heroku magically simplified deploying a new version of your application; now you only needed to type git push heroku. Some of the best-known web companies originated on Heroku.
These advances made deploying applications at any scale—large or small—much easier and more affordable. They led to the creation of many new businesses and powered a radical shift in how companies treated infrastructure, moving it from a capital expense to a variable operating