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.com 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.
AWS launched Amazon S3 in the United States on March 14, 2006, then in Europe in November 2007.
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:
http://s3.amazonaws.com/bucket/key (for a bucket created in the US East (N. Virginia) region)
http://s3.dualstack.region.amazonaws.com/bucket/key (for requests using IPv4 or IPv6)
http://bucket/key (where bucket is a DNSCNAME record pointing to bucket.s3.amazonaws.com)
https://access_point_name-account ID.s3-accesspoint.region.amazonaws.com (for requests via an access point granting restricted access to a bucket)
Amazon S3 can be used to replace significant existing (static) web-hosting infrastructure with HTTP client accessible objects. The Amazon AWS authentication mechanism allows the bucket owner to create an authenticated URL which is valid for a specified amount of time.
Every item in a bucket can also be served as a BitTorrent feed. The Amazon S3 store can act as a seed host for a torrent and any BitTorrent client can retrieve the file. This can drastically reduce the bandwidth cost for the download of popular objects. While the use of BitTorrent does reduce bandwidth, AWS does not provide native bandwidth limiting and, as such, users have no access to automated cost control. This can lead to users on the free-tier of Amazon S3, or small hobby users, amassing dramatic bills. AWS representatives have stated that a bandwidth limiting feature was on the design table from 2006 to 2010, but in 2011 the feature is no longer in development.
A bucket can be configured to save HTTP log information to a sibling bucket; this can be used in data mining operations.
There are various User Mode File System (FUSE)-based file systems for Unix-like operating systems (Linux, etc.) that can be used to mount an S3 bucket as a file system such as S3QL. The semantics of the Amazon S3 file system are not that of a POSIX file system, so the file system may not behave entirely as expected.
Amazon S3 provides the option to host static HTML websites with index document support and error document support. Websites hosted on S3 may designate a default page to display and another page to display in the event of a partially invalid URL, such as a 404 error, which provide useful content to visitors of a URL containing a CNAME record hostname rather than a direct Amazon S3 bucket reference when the URL does not contain a valid S3 object key, such as when a casual user initially visits a URL that is a bare non-Amazon hostname.
Amazon S3 logs
Amazon S3 allows users to enable or disable logging. If enabled, the logs are stored in Amazon S3 buckets which can then be analyzed. These logs contain useful information such as:
Amazon S3 provides an API for developers. The AWS console provides tools for managing and uploading files but it is not capable of managing large buckets or editing files. Third-party websites or software some software have the capability to edit files on Amazon S3.
Amazon S3 storage classes
Amazon S3 offers four different storage classes that offer different levels of durability, availability, and performance requirements.
Amazon S3 Standard is the default class.
Amazon S3 Standard Infrequent Access (IA) is designed for less frequently accessed data. Typical use cases are backup and disaster recovery solutions.
Amazon S3 One Zone-Infrequent Access is designed for data that is not often needed but when required, needs to be accessed rapidly. Data is stored in one zone and if that zone is destroyed, all data is lost.
Amazon Glacier is designed for long-term storage of data that is infrequently accessed and where retrieval latency of minutes or hours is acceptable. "Glacier Deep Archive" is an alternative with a retrieval time of at least 12 hours, but 1/4th the price. It is intended as an alternative to magnetic tape libraries, and is designed for long term retention of data for 7 to 10 years.
Photo hosting service SmugMug has used Amazon S3 since April 2006. They experienced a number of initial outages and slowdowns, but after one year they described it as being "considerably more reliable than our own internal storage" and claimed to have saved almost $1 million in storage costs.
Bitcasa, and Tahoe-LAFS-on-S3, among others, use Amazon S3 for online backup and synchronization services. In 2016, Dropbox stopped using Amazon S3 services and developed its own cloud server.
Swiftype's CEO has mentioned that the company uses Amazon S3.
Amazon S3 was used by some enterprises as a long term archiving solution until Amazon Glacier was released in August 2012.
The API has become a popular method to store objects. As a result, many applications have been built to natively support the Amazon S3 API which includes applications that write data to Amazon S3 and Amazon S3-compatible object stores:
The broad adoption of Amazon S3 and related tooling has given rise to competing services based on the S3 API. These services use the standard programming interface; however, they are differentiated by their underlying technologies and supporting business models. A cloud storage standard (like electrical and networking standards) enables competing service providers to design their services and clients using different parts in different ways yet still communicate and provide the following benefits:
Increase competition by providing a set of rules and a level playing field, encouraging market entry by smaller companies which might otherwise be precluded.
Encourage innovation by cloud storage & tool vendors, & developers because they can focus on improving their own products and services instead of focusing on compatibility.
Allow economies of scale in implementation (i.e., if a service provider encounters an outage or as clients outgrow their tools and need faster operating systems or tools, they can easily swap out solutions).
Provide timely solutions for delivering functionality in response to demands of the marketplace (i.e., as business growth in new locations increases demand, clients can easily change or add service providers simply by subscribing to the new service).
At AWS Summit 2013 NYC, CTO Werner Vogels announces 2 trillion objects stored in S3.
Amazon Web Services introduced Amazon S3 in 2006.
Amazon S3 is reported to store more than 2 trillion objects as of April 2013[update]. This is up from 10 billion objects as of October 2007, 14 billion objects in January 2008, 29 billion objects in October 2008, 52 billion objects in March 2009, 64 billion objects in August 2009, and 102 billion objects in March 2010. In November 2017 AWS added default encryption capabilities at bucket level. 
^Ibm; Emc; Netapp; Seagate; Hp; Hill, Seagate rolls storage kit for manufacturers down Dot. "CTERA Networks offers up in-cloud server backup". Spectralogic CTO talks up hybrid flash-tape cartridge. Welcome tape robot overlords and backup, CTERA Networks offers up in-cloud server. Archived from the original on 2016-05-06. Retrieved .
^Committee on Standards Workshop Planning, Board on Telecommunications and Computer Applications, Commission on Engineering and Technical Systems, National Research Council (1990). Crossroads of Information Technology Standards. Washington, DC: The National Academies Press, 1990. pp. 36-37. Archived from the original on 2014-03-25. Retrieved .CS1 maint: uses authors parameter (link)