Amazon S3 or Amazon Simple Storage Service is a service offered by Amazon Web Services (AWS) that provides object storage through a web service interface. Amazon S3 uses the same scalable storage infrastructure that Amazon uses to run its global e-commerce network. Amazon S3 can be employed to store any type of object, which allows for uses like storage for Internet applications, backup and recovery, disaster recovery, data archives, data lakes for analytics, and hybrid cloud storage.

Although Amazon Web Services (AWS) does not publicly provide the details of S3's technical design, Amazon S3 manages data with an object storage architecture that aims to provide scalability, high availability, and low latency with 99.999999999% durability and between 99.95% to 99.99% availability (though there is no service-level agreement for durability).

The basic storage units of Amazon S3 are objects which are organized into buckets. Each object is identified by a unique, user-assigned key. Buckets can be managed using either the console provided by Amazon S3, programmatically using the AWS SDK or with the Amazon S3 REST application programming interface (API). Objects can be managed using the AWS SDK or with the Amazon S3 REST API and can be up to five terabytes in size with two kilobytes of metadata. Additionally, objects can be downloaded using the HTTP GET interface and the BitTorrent protocol.

Requests are authorized using an access control list associated with each object bucket and support versioning which is disabled by default. Since buckets are typically the size of an entire file system mount in other systems, this access control scheme is very coarse-grained. In other words, unique access controls cannot be associated with individual files. Bucket names and keys are chosen so that objects are addressable using HTTP URLs: