Amazon S3 can be used for storing data for application usage as well as for backing up and archiving the data. It doesn't bind the files to be stored. We can store any file, which are treated as objects, in Amazon S3. Amazon uses S3 to run its own global network of websites (http://docs.aws.amazon.com/AmazonS3/latest/dev/Welcome.html).

We can store as much data as we want in Amazon S3; it doesn't restrict a user from storing any. Amazon charges the user for the storage that is actually used. So, it is quite inexpensive for the user, because he/she doesn't need to purchase storage externally.

Amazon S3 keeps the redundant data across multiple data centers for high scalability. The user can select the region where his/her data will be stored. This reduces the latency in storing and retrieving the data. Amazon S3 also offers security on the objects. The user can make the object publicly or privately accessible. We can also store encrypted data in Amazon S3, and it guarantees a server uptime of 99.9 percent.

Amazon S3 can be integrated with any application or services offered by Amazon, such as Amazon Elastic Compute Cloud (Amazon EC2), Amazon Elastic Block Storage (Amazon EBS), Amazon Glacier, and so on.

Subscribing to Amazon S3 is free, and you just need to pay for the bandwidth that you use and for whatever you are actually hosting. Small start-ups usually don't have an infrastructure to store their huge amount data. So, they opt for Amazon S3 to store their images, videos, files, and so on to minimize the costs.

Amazon S3 also provides website hosting services. You can directly upload your pages in Amazon S3, and map it to your domain.