What Happens When You Upload a File?

Web browsers let you upload files to a server using a form and file input control. The browser sends an HTTP request with the body of the request containing the encoded contents of the form. In this tutorial you'll see what these requests look like on the browser and on the server. We'll explore the difference between the two main form encoding types: application/x-www-form-urlencoded and multipart/form-data. Regardless of what framework or library you use, this is the foundation of how files are uploaded on the web using the HTTP protocol.

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