What is S3 in AWS? An Introduction

Reviewed May 20, 2026. S3 concepts remain stable, but access-control and static-website patterns have changed over time. Use Origin Access Control for private S3 REST origins behind CloudFront unless you are intentionally maintaining a legacy OAI design.

Use this guide to understand how S3 buckets, policies, and storage classes support secure and scalable business data workflows.

S3 storage class snapshot

Storage class	Best fit	Access pattern
S3 Standard	Frequently accessed objects	Low-latency access with no retrieval planning
S3 Intelligent-Tiering	Unknown or changing access patterns	AWS moves objects between tiers based on access
S3 Standard-IA or One Zone-IA	Infrequently accessed objects	Lower storage cost with retrieval charges
S3 Glacier classes	Archive and long-term retention	Retrieval time and cost depend on archive class

If you’re running a business, you’re probably using Amazon Web Services (AWS) in some way or another. AWS is a suite of cloud-based services that allow enterprises to run their operations more efficiently and cost-effectively. One of the most popular services offered by AWS is S3, which is short for Simple Storage Service. It is a popular choice for businesses because it is cost-effective and scalable. You can use S3 to store any data, including photos, videos, documents, and more. Companies can use S3 to store data centrally and share it with employees or customers. In this blog post, we will discuss what S3 is and how it can be used by businesses to store and share data. We’ll also cover some of the most important capabilities of S3 and how to use them effectively.

What is S3?

S3 is a cloud-based storage service that provides businesses a cost-effective and efficient way to store and share data. The service is simple to use, making it a popular choice for businesses of all sizes. S3 provides a variety of capabilities that make it an ideal storage solution for businesses, including high availability, durability, scalability, security, and cost-effectiveness.

How to use S3 for your business

One can use S3 for various business purposes, including data backup and recovery using a service like AWS Storage Gateway connecting your local file storage to S3 and file sharing, facilitated by S3 pre-signed URLs or CloudFront signed URLs and signed cookies. It can be configured as an origin for CloudFront to deliver static assets like CSS, JavaScript, images, and PDF files for websites, and it can even host entire static websites directly on a domain name, bypassing web servers completely. The service is easy to use and can be accessed from any internet-connected device. To start with S3, businesses create an AWS account and upload their data.

What is a bucket in Amazon S3?

S3 is based on storage containers called “buckets.” One must name an S3 bucket uniquely as the S3 namespace is global. You create your bucket in a particular region in AWS, and your data stays in that region, AWS S3 region is about data residency, but the name must be unique across all AWS customer accounts and all regions. No two buckets can share the same name.

Within buckets, files or “objects” are stored in a flat structure and named using a convention that includes an object key name representing a folder structure. For example, directory/subdirectory/filename.txt is an object key or S3 path that is a folder structure, but since S3 buckets have a flat structure, the full key, including forward-slashes are part of the filename.

You can click through a bucket as though you are navigating a folder structure, so S3 buckets feel much like a typical filesystem.

The most important capabilities of S3

S3 provides many capabilities that make it an ideal storage solution for businesses. These capabilities include high availability, durability, scalability, security, and cost-effectiveness. It also provides several storage classes designed for different purposes, from frequent access to archival storage, and each class has its own capabilities. In general though, S3 provides the following:

• High availability: S3 is designed to ensure that data is always available when needed. S3 Standard is designed for 99.99% availability, and the Amazon S3 service level agreement commits to 99.9% monthly uptime before service credits apply, so businesses can be confident that their data will be accessible when needed.

• High durability: S3 provides 99.999999999% or what they call “eleven 9’s” durability, so you can rest easy that the odds of losing files are about as slim as winning the lottery in a given year.

• Scalability: S3 is a scalable storage solution that can grow with your business. The service can add more storage capacity as needed, making it a flexible solution for businesses of all sizes.

• Security: S3 is a secure storage solution, offering data encryption and access control capabilities. This ensures that only authorized users can access your data, keeping it safe from unauthorized access.

• Cost-effectiveness: S3 is a cost-effective storage solution. You only pay for the storage you use, and there are no upfront costs.

How to use S3 effectively

S3 is a solid storage solution that provides businesses many benefits. To get the most out of the service, it’s essential to use S3 effectively. Here are some tips for using S3 effectively:

Control access to your bucket

Make sure you have set the correct access permissions for your use case. For private S3 bucket origins behind CloudFront, use the S3 REST endpoint, keep the bucket private, and use CloudFront origin access control in the bucket policy. AWS recommends OAC for S3 origins because it supports all S3 Regions, SSE-KMS, and dynamic requests. Direct S3 static website hosting uses the S3 website endpoint, which is treated as a custom origin and cannot use OAC or OAI in the same way; website endpoints require public-read style access for the hosted content. If the bucket is being used as internal company storage, it should likewise have the appropriate restrictions in the bucket policy.

Use lifecycle management

S3 provides lifecycle management capabilities, which allow businesses to automate the process of moving data between different storage tiers. This can help optimize costs by moving data not frequently accessed to cheaper storage tiers.

Use versioning

S3 can create multiple data versions, allowing businesses to roll back to previous versions if necessary. This can be useful for restoring accidentally deleted data or reverting to a prior version of a file.

The shared responsibility model

One important thing to be aware of as an AWS customer is that there is a division of responsibility between customers and AWS. In the Shared Responsibility Model Amazon is responsible for the security of the cloud, data centres, computer hardware, system upgrades for managed services, etc., but the client is responsible for security in the cloud. This means you must ensure that you have properly secured your cloud storage and other resources like EC2 instances, keeping credentials and SSH keys private, and appropriate user and resource policies (like bucket policies) to keep your data confidential.

While AWS has made managing permissions of S3 buckets much easier in recent years, it wouldn’t hurt to contact us to help ensure all those ducks are lined up. We offer complete cloud migration services to ease the process.

Final note

Start with clear bucket naming and access policies, enable lifecycle rules and versioning, then monitor storage class usage to optimize resilience and cost over time.

Frequently asked

Frequently asked questions

1. 01

   What is Amazon S3 used for?

   Amazon S3 is used for object storage, including backups, static website assets, application files, logs, analytics data, and data lake storage.

2. 02

   Is Amazon S3 the same as a file system?

   No. S3 stores objects in buckets. It is not a mounted block or shared file system like EBS or EFS, although many tools can read and write objects through S3 APIs.