Compute Basics (VMs / Instances)

Rent a computer by the hour

A virtual machine (VM), often called an instance, is a software-defined computer with a chosen CPU, memory, disk, and operating system image. You start it, connect over SSH or RDP, install software, and stop or terminate it when finished.

Choose size and image

• Instance type or size sets vCPU and RAM
• An image (AMI, marketplace image, or custom image) defines the OS and base software
• Ephemeral vs persistent disks affect whether data survives a stop or recreate
• Public IP or bastion access is how you reach the machine remotely

Respect the lifecycle

Running VMs bill for time. Stopping may still charge for attached disks. Terminating usually deletes the instance; attached storage policy decides whether disks remain. Tag resources with owner and purpose so you can find orphans later.

Launch vocabulary across clouds

AWS calls them EC2 instances, Azure uses Virtual Machines, and GCP uses Compute Engine instances. The CLI patterns below are illustrations—always follow current docs for flags and images.

# Conceptual shapes (details vary by account and image)
# aws ec2 run-instances --instance-type t3.micro --image-id ami-...
# az vm create --name demo --resource-group rg --image Ubuntu2204 --size Standard_B1s
# gcloud compute instances create demo --machine-type e2-micro --zone europe-west1-b