What is an EC2 instance?

An EC2 instance refers to a virtual server within Amazon's Elastic Compute Cloud (EC2), which is a core service offered by AWS for delivering scalable computing power. EC2 enables users to deploy and manage server instances in the cloud virtually, providing the flexibility to run applications and workloads as needed without investing in physical hardware.

Instances can be customized according to CPU, memory, and storage requirements, allowing users to choose from a variety of instance types tailored for different needs, whether they're running a simple web application or processing large datasets. This flexibility, along with the ability to scale resources up or down, makes EC2 an essential service for developers and businesses looking to harness the power of cloud computing.

The other options presented do not accurately represent an EC2 instance, as they refer to different aspects of AWS services not directly related to virtual servers in cloud computing.