Amazon Elastic Compute Cloud (Amazon EC2) is a web service that provides resizeable compute capacity in the cloud. It is designed to make web-scale computing easier for developers.
Amazon EC2 instances are the fundamental building block for your computing needs in the AWS cloud. You can think of instances as virtual servers that can run applications. Instances are created from an Amazon Machine Image (AMI) and choosing an appropriate instance type. An AMI is a template that contains a software configuration, including an operating system, which defines your operating environment. You can select an AMI provided by AWS, our user community, or on the AWS Marketplace. You can also create and optionally share your own AMIs. A single AMI can be used to launch one or thousands of instances.