EC2 (Elastic Compute Cloud) is an AWS web service that provides secure, resizable compute capacity in the cloud as virtual servers.

The main criteria when choosing an EC2 instance include computing power (vCPUs), memory (RAM), storage options, and network performance.

A key pair consists of a public key and a private key used to securely connect to your EC2 instance via SSH or RDP.

A security group acts as a virtual firewall for your EC2 instances to control inbound and outbound network traffic.

An instance type defines the specific combination of CPU, memory, storage, and networking capacity allocated to your virtual server.