HTML and HTTP both support the concept of a file upload. You can choose a file with the file upload form element, and when you submit the form the file is sent to the web server.

To enable this upload an addition to the possible methods of form encoding was made. As well as the standard application/xxx-www-form-urlencoded type the multipart/form-data was added. Unfortunately although the Microsoft web browsers support this method the Microsoft ASP components do not.

To work round this problem ImageGlue is supplied with ABCUpload which allows you to extract uploaded files from multipart data. The ABCUpload documentation describes how it works.