S3 can be used as a frontend to our serverless environment. As we mentioned at the beginning of this chapter, and as we will demonstrate in our example later on, we can host a static website straight from S3 by providing an index document and uploading all our static website files. These files can also contain client-side scripts to extend their capabilities, and we can also give our end users the ability to upload data to S3. Any upload to an S3 bucket can be easily made to trigger a function that will process any information held in the uploaded file. The uploaded file can, for instance, deliver responses from a web form or it could be an image, video, or other file being uploaded that needs to be processed. Whatever the content, S3 is our starting point in building a web-scale serverless environment. The serverless function (or multiple functions) hosted on Lambda (which we will cover in a later chapter) can then take the place of our server-side processing features and perform any processing that would usually be processed within a web server: they can reply to the user, record data in databases, or perform powerful transformations on data and interact with other AWS services in the backend.