form data enctype

http://stackoverflow.com/questions/4526273/what-does-enctype-multipart-form-data-mean

When submitting a form, you're trying to say your browser to send via the HTTP protocol a message on the network properly enveloped in a TCP/IP protocol message structure. When sending data, you can use POST or GET modes to send data using HTTP protocol. POST tells your browser to build an HTTP message and put all content in the header of the message ( a very useful way of doing things, more safe and also flexible). GET has some constraints about data representation and length.

When sending a file, it is necessary to tell HTTP protocol that you are sending a file having several characteristics and information inside it. In this way it is possible to consistently send data to receiver and let him open the file with the current format and so on... This is a requirement from the HTTP protocol as shown here

You cannot send files using default send enctype parameters because your receiver might encounter problems reading it (consider that a file is a descriptor for some data for a specific operating system, if you see things this way, maybe you'll understand why it is so important to specify a different enctype for files).

This way of doing things also ensures that some security algorithms work on your messages. This information is also used by application-level routers in order to act as good firewalls for external data.

Well, as you can see, it is not a stupid thing using a specific enctype for files.