Amazon s3 is a remote file storing system. It is totally different from Normal Servers like Apache, FTP server etc. If your site burns more bandwidth due to multimedia contents such a video, image, audio etc, the maintenance cost will be very high. For a limited number of page views, local file saving mechanism is ok. Because the cost of bandwidth is comparatively low. But when the data transfer rate become higher, the bandwidth cost should be considered.
In such a case instead of saving files or images in local servers, You can use Amazon s3 server (S3 stands for Simple Storage Service). For this you have do two things
1) Register on http://www.amazon.com/gp/browse.html?node=16427261
2) Use api for uploading your files into s3
The file uploading, deleting etc functions are not like normal FTP. S3 uses different services for this purpose. Service means Webservices. Apis are available for ASP,ASP.net PHP, C#, Ruby , JAVA, PERL etc
Developers, please use this link for details:http://docs.amazonwebservices.com/AmazonS3/2006-03-01/gsg/?ref=get-started