Compute

Virtual servers (EC2)

An EC2 instance is a virtual machine running in a cloud data centre. You choose its operating system, size and network settings, and pay only while it runs.

Instance types

An instance type fixes the amount of CPU and memory. Small burstable types such as t3.micro suit labs and light workloads; larger families are tuned for compute, memory or storage.

Key pairs and access

Linux instances are reached over SSH using a private key. For Windows instances, the same key decrypts the generated Administrator password, which is then used over RDP.

Lifecycle

• Running – billed for compute.
• Stopped – no compute charge, but attached volumes are still stored and billed.
• Terminated – the instance is deleted; volumes marked delete-on-termination go with it.

Good habits

Stop what you are not using, terminate what you no longer need, and check volumes and snapshots afterwards — they are billed separately.

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