Amazon Elastic Compute Cloud (EC2) is the core compute service of AWS, providing resizable virtual machines in the cloud. It is the AWS equivalent of Azure Virtual Machines .
Term Description Instance A running virtual machine AMI Amazon Machine Image — the OS + software template for an instance Instance Type The hardware spec (CPU, RAM, GPU, network) Key Pair SSH public/private key for secure access Security Group Stateful firewall controlling inbound/outbound traffic Elastic IP Static public IP address that you own User Data Script that runs on first boot to configure the instance
Family Optimized For Example Types t (General purpose, burstable)Dev/test, low-cost t3.micro, t4g.smallm (General purpose, balanced)Web servers, small databases m6i.large, m7g.xlargec (Compute optimized)CPU-intensive apps, HPC c6i.large, c7g.2xlarger (Memory optimized)In-memory databases, caches r6i.large, r7g.4xlargep / g / trn (Accelerated)ML training, GPU workloads p4d.24xlarge, g5.xlargei / d (Storage optimized)High I/O, data warehouses i4i.large, d3.xlarge
t3.micro is included in the AWS Free Tier (750 hours/month for 12 months).
Model Description Best For On-Demand Pay by the second, no commitment Dev/test, unpredictable workloads Reserved Instances 1 or 3-year commitment, up to 72% discount Steady-state production workloads Savings Plans Flexible commitment on compute spend, up to 66% off Flexible reserved-like pricing Spot Instances Spare capacity at up to 90% discount — can be interrupted Fault-tolerant batch, ML training Dedicated Hosts Physical server dedicated to you Licensing compliance (Windows Server, SQL Server) Dedicated Instances Your instances run on dedicated hardware Compliance, isolation
Storage Description Persistence EBS (Elastic Block Store) Network-attached block storage — primary OS disk Persists after stop/terminate (configurable) Instance Store Physically attached ephemeral storage Lost when instance stops EFS (Elastic File System) Shared NFS storage across multiple instances Persistent, shared S3 Object storage accessed via API Persistent, not a filesystem
Pending → Running → Stopping → Stopped → Terminated
Stop — Saves state, no billing for compute (EBS still billed)Terminate — Permanently deleted (EBS may be deleted depending on config)Reboot — Restarts the OS, instance stays on the same host
Each EC2 instance belongs to a VPC and a Subnet
Security Groups control traffic (default: deny all inbound)Public instances need an Internet Gateway and a public IP or Elastic IP
Private instances use a NAT Gateway for outbound internet access
ENI (Elastic Network Interface) — Virtual network card that can be moved between instances
Auto Scaling Groups (ASG) automatically adjust the number of instances based on demand:
Define minimum, desired, and maximum instance counts
Scale out (add instances) on high CPU/memory/custom metric
Scale in (remove instances) when demand drops
Integrated with Elastic Load Balancer (ELB) for traffic distribution
Feature AWS EC2 Azure VM VM image format AMI Azure Managed Image / Marketplace Disk type EBS (gp3, io2) Managed Disks (Standard SSD, Premium SSD) Instance metadata 169.254.169.254 IMDS 169.254.169.254 IMDS Reserved pricing Reserved Instances / Savings Plans Reserved VM Instances Auto scaling Auto Scaling Group (ASG) Virtual Machine Scale Sets (VMSS) Load balancer ALB / NLB Azure Load Balancer / Application Gateway Static IP Elastic IP Static Public IP
--image-id ami-0abcdef1234567890 \
--instance-type t3.micro \
--security-group-ids sg-0abc123 \
--subnet-id subnet-0abc123
aws ec2 describe-instances \
--filters " Name=instance-state-name,Values=running " \
--query ' Reservations[*].Instances[*].[InstanceId,InstanceType,PublicIpAddress] ' \
aws ec2 stop-instances --instance-ids i-0abc1234567890
aws ec2 terminate-instances --instance-ids i-0abc1234567890