The Amazon Elastic Compute Cloud service, often referred to as Amazon EC2, is a cloud computing web service. It can be used by developers to perform web-scale testing in a large capacity environment. It can can also be used to quickly boot new server instances, offers web scaling capacities and can offer fail-safe application redundancy. The basis of the service is to offer server capacity on an as-needed basis.http://aws.amazon.com/ec2/

The EC2 service offers complete control to users, including root access. Developers can also select between multiple operating systems, software packages, storage and memory size. It interacts seamlessly with the Amazon Simple Storage Service, the Amazon Simple DB and the Amazon Simple Queue Service. Amazon touts an SLA, or service level agreement, of 99.95 percent service availability.http://aws.amazon.com/ec2/

One of the main benefits of the service, according to Amazon, is computing affordability. EC2 services can be purchased as on-demand instances, reserved instances for guaranteed space and time or as an auction-style spot instance.http://http://aws.amazon.com/ec2/purchasing-options/

1. Standard Instances- Offered in small, large and extra large, these instances range from 1.7G to 15 GB of memory on a 64-bit platform with multiple cores available.http://aws.amazon.com/ec2/
2. Micro Instances- Designed for small usage and occasional burst CPU needs for websites or low throughput applications.http://aws.amazon.com/ec2/
3. High-Memory Instances- Available in Extra large, double extra large and quadruple extra large sizes from 17.1 GB to 68.4 GB of memory capacity. Primarily used for high throughput applications such as database caching needs.http://aws.amazon.com/ec2/
4. High-CPU Instances- Designed for compute-intensive application needs with up to 20 EC2 compute unities available.http://aws.amazon.com/ec2/
5. Cluster Compute Instances- Designed for network-bound and applications that need high network performance. Provides 23 GB of memory, 1690 GB of storage, 33.5 EC2 compute units over a 10 Gigabit Ethernet connection.http://aws.amazon.com/ec2/