Amazon Elastic Compute Cloud (Amazon EC2) is an AWS service that provides on-demand, scalable computing capacity as virtual servers called instances. You choose and configure those servers for your workload; AWS operates the underlying cloud infrastructure.
What does “Elastic Compute Cloud” mean?
Elastic means you can add or reduce computing capacity as your needs change. For example, a service might use more servers during a traffic spike and fewer when demand falls. EC2 makes that adjustment possible, but it does not mean every resource expands automatically: scaling depends on your configuration and, where appropriate, related services such as EC2 Auto Scaling. AWS describes EC2 as providing on-demand, scalable computing capacity in its EC2 user guide.
Compute is the processing capacity used to run software and workloads. Cloud means you obtain that capacity from AWS instead of buying and operating the physical server hardware yourself. You still manage your instances and their configurations; AWS supplies the infrastructure beneath them.
What is an EC2 instance?
An EC2 instance is a virtual server in AWS. You launch it from an Amazon Machine Image (AMI), a template that provides an operating system and may also include applications or an application server. You then choose the instance’s resource configuration, set up access and security, connect to it, and install or update software as needed. AWS explains the launch process in its instance documentation.
Terms you will encounter
- AMI: The starting image used to launch an instance.
- Instance type: The configuration that determines the instance’s available balance of compute, memory, storage, and network capabilities.
- Amazon EBS volume: Persistent block storage that can be used with an instance.
- Instance store: Temporary storage. AWS says its data is deleted when an instance is stopped, hibernated, or terminated.
- Key pair: Login credentials: AWS stores the public key, and you are responsible for keeping the private key secure.
- Security group: A virtual firewall that controls permitted traffic to and from instances.
- EC2 Auto Scaling: A related service that helps maintain an appropriate number of instances for an application’s load.
These definitions and storage and access details are covered in the EC2 concepts guide.
How do you choose an EC2 instance?
Choose an instance type according to what your application needs, rather than looking for a single “best” option. Instance types differ in compute, memory, storage, and network capabilities. AWS recommends reviewing the specifications and benchmarking suitable candidates with your own workload; current options and availability can vary by Region. See AWS’s instance type guide for the available families and selection details.
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How does EC2 pricing work?
EC2 does not have one flat price for every instance. AWS lists several purchasing options, including On-Demand Instances, Savings Plans, Reserved Instances, Spot Instances, Dedicated Hosts, and On-Demand Capacity Reservations. The relevant option depends on your usage pattern, capacity requirements, configuration, and Region. Check AWS EC2 pricing or use the AWS Pricing Calculator for an estimate based on your planned setup.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.When might Lightsail be a better fit?
EC2 is one AWS compute option, not the only one. AWS positions Amazon Lightsail for quickly deploying websites and web applications with a low, predictable monthly price. It may suit a project where simpler setup and price predictability matter more than the control and configuration choices available through EC2. That positioning does not establish that Lightsail is universally cheaper or better; the right fit depends on the workload. AWS provides a Lightsail-versus-EC2 comparison for evaluating the services.
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