Amazon EC2 stands for Elastic Cloud Computing. It is a web service that provides application hosting on virtual machines called instances using simple interfaces. Main benefits are reduced cost of virtual machines compared to physical ones, fast and simple maintenance and no downtime.
Amazon EC2 provides elastic web-scale computing which enables you to increase or decrease capacity within minutes.
You have complete control over your instances as you would have over physical ones. It is a flexible cloud hosting service that gives you choice of instance types, operating systems and software packages.
Amazon EC2 is highly secure and works in conjunction with Amazon VPC (Virtual Private Cloud) to provide security and robust networking functionality.
It is very simple to start with and there is an option to try Amazon EC2 for free.