The Amazon Elastic Compute Cloud (EC2) is the central part of the Amazon cloud offering. This service provides a virtual computer that customers can request and use as part of their cloud workloads. 

There are several different types of EC2 offerings depending on the customer needs. For example, there are EC2 instances that are specific to memory-intensive applications, or another type that is specific to a compute-intensive application. And within each type of EC2 instance, you can further configure the system to find one that matches the number of CPUs, the amount of RAM, size of the disk storage, and the network connectivity types that meet your needs.

Amazon charges for the use of the EC2 instance requested. The usage is billed on per-second increments. Different types of EC2 instances will have different pricing. It can be as low as a few pennies per hour to over $100 per hour. Also, depending on your needs, you can request a reserved instance (cheaper) or an on-demand instance (more expensive).