Amazon S3 Introduction

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What is Amazon S3?

Amazon Simple Storage Service is storage for the Internet. It is designed to make web-scale computing easier for developers. Amazon S3 has a simple web services interface that you can use to store and retrieve any amount of data, at any time, from anywhere on the web. It gives any developer access to the same highly scalable, reliable, fast, inexpensive data storage infrastructure that Amazon uses to run its own global network of web sites. The service aims to maximize benefits of scale and to pass those benefits on to developers. This guide explains the core concepts of Amazon S3, such as buckets, access points, and objects, and how to work with these resources using the Amazon S3 application programming interface (API).

Introduction to Amazon S3

This introduction to Amazon Simple Storage Service (Amazon S3) provides a detailed summary of this web service. After reading this section, you should have a good idea of what it offers and how it can fit in with your business.

Overview of Amazon S3 and this guide

Amazon S3 has a simple web services interface that you can use to store and retrieve any amount of data, at any time, from anywhere on the web.

This guide describes how you send requests to create buckets, store and retrieve your objects, and manage permissions on your resources. The guide also describes access control and the authentication process. Access control defines who can access objects and buckets within Amazon S3, and the type of access (for example, READ and WRITE). The authentication process verifies the identity of a user who is trying to access Amazon Web Services (AWS).

Advantages of using Amazon S3

Amazon S3 is intentionally built with a minimal feature set that focuses on simplicity and robustness. Following are some of the advantages of using Amazon S3:

  • Creating buckets – Create and name a bucket that stores data. Buckets are the fundamental containers in Amazon S3 for data storage.

  • Storing data – Store an infinite amount of data in a bucket. Upload as many objects as you like into an Amazon S3 bucket. Each object can contain up to 5 TB of data. Each object is stored and retrieved using a unique developer-assigned key.

  • Downloading data – Download your data or enable others to do so. Download your data anytime you like, or allow others to do the same.

  • Permissions – Grant or deny access to others who want to upload or download data into your Amazon S3 bucket. Grant upload and download permissions to three types of users. Authentication mechanisms can help keep data secure from unauthorized access.

  • Standard interfaces – Use standards-based REST and SOAP interfaces designed to work with any internet-development toolkit.


    SOAP support over HTTP is deprecated, but it is still available over HTTPS. New Amazon S3 features will not be supported for SOAP. We recommend that you use either the REST API or the AWS SDKs.

Amazon S3 concepts

This section describes key concepts and terminology you need to understand to use Amazon S3 effectively. They are presented in the order that you will most likely encounter them.


A bucket is a container for objects stored in Amazon S3. Every object is contained in a bucket. For example, if the object named photos/puppy.jpg is stored in the awsexamplebucket1 bucket in the US West (Oregon) Region, then it is addressable using the URL

Buckets serve several purposes:

  • They organize the Amazon S3 namespace at the highest level.

  • They identify the account responsible for storage and data transfer charges.

  • They play a role in access control.

  • They serve as the unit of aggregation for usage reporting.

You can configure buckets so that they are created in a specific AWS Region. For more information, see Accessing a Bucket. You can also configure a bucket so that every time an object is added to it, Amazon S3 generates a unique version ID and assigns it to the object. For more information, see Using Versioning.

For more information about buckets, see Working with Amazon S3 Buckets.


Objects are the fundamental entities stored in Amazon S3. Objects consist of object data and metadata. The data portion is opaque to Amazon S3. The metadata is a set of name-value pairs that describe the object. These include some default metadata, such as the date last modified, and standard HTTP metadata, such as Content-Type. You can also specify custom metadata at the time the object is stored.

An object is uniquely identified within a bucket by a key (name) and a version ID. For more information, see Keys and Using Versioning.


A key is the unique identifier for an object within a bucket. Every object in a bucket has exactly one key. The combination of a bucket, key, and version ID uniquely identify each object. So you can think of Amazon S3 as a basic data map between "bucket + key + version" and the object itself. Every object in Amazon S3 can be uniquely addressed through the combination of the web service endpoint, bucket name, key, and optionally, a version. For example, in the URL, "doc" is the name of the bucket and "2006-03-01/AmazonS3.wsdl" is the key.

For more information about object keys, see Object Keys.


You can choose the geographical AWS Region where Amazon S3 will store the buckets that you create. You might choose a Region to optimize latency, minimize costs, or address regulatory requirements. Objects stored in a Region never leave the Region unless you explicitly transfer them to another Region. For example, objects stored in the Europe (Ireland) Region never leave it.