S3 means Simple Storage Service
S3 is a product from Amazon and it is an online storage service. You can see it as a hard drive that is somewhere else in the world. The difference with a hard drive is that there is no storage limit here. If you put more on it, you use more space, with Amazon you only pay for what you use. If you use 5 gigabytes, you pay less than if you use 500 gigabytes. It's a good and inexpensive way to backup your photo or video material online.
Getting started with Amazon S3 [YouTube] 1qrjFb0ZTm8 [/youtube]