Overview of AWS Elastic Compute Cloud (EC2) Purpose and Pricing

EC2 instances are what we can think of as traditional servers. You can choose your hardware options and OS. Pricing is based on server uptime and if you control when that uptime is.

You can see the details of their pricing here, Amazon EC2 pricing. As you can see there is a free plan that gives you 750 hours of Linux and Windows t2.micro instances a month for the first year.