AWS Elastic Compute Cloud (AWS EC2) is a web service that provides resizable compute capacity in the cloud.
EC2 provides you with complete control of your computing resources. AWS EC2 reduces the time required to obtain and boot new server instances to minutes, allowing you to quickly scale capacity, both up and down, as your computing requirements change. AWS EC2 changes the economics of computing by allowing you to pay only for capacity that you actually use. AWS EC2 provides developers the tools to build failure resilient applications and isolate themselves from common failure scenarios.
Elastic Web-Scale Computing
AWS EC2 enables you to increase or decrease capacity within minutes, not hours or days. You can commission one, hundreds or even thousands of server instances simultaneously. Of course, because this is all controlled with web service APIs, your application can automatically scale itself up and down depending on its needs.