The Amazon Simple Storage Service (Amazon S3) is a scalable, high-speed, low-cost Web-based service designed for online backup and archiving of data and application programs. According to the Amazon Web services pages, the S3 was intentionally designed with a minimal feature set and was created to make Web-scale computing easier for developers.
The service gives subscribers access to the same systems that Amazon uses to run its own Web sites. The S3 allows uploading, storage and downloading of practically any file or object up to five gigabytes (5 GB) in size. Amazon.com imposes no limit on the number of items that a subscriber can store.
Subscribers can choose to keep their data private or make it publicly accessible. Users can also, if they so desire, encrypt data prior to storage. Rights may be specified for individual users. When a subscriber stores data on the S3, Amazon.com tracks usage for billing purposes but does not otherwise access the data unless required to do so by law.