enctype

multipart/form-data is a lot bulkier than application/x-www-form-urlencoded; the latter is just a bunch of keys and values (and can be parsed the same way whether for GET or POST), whereas the former requires full MIME support, and is thus more useful when you have data that can’t simply be represented as key/value pairs.

Yes, it is. Here’s a cite from the W3 HTML forms specification: The default value for this attribute is “application/x-www-form-urlencoded”. The value “multipart/form-data” should be used in combination with the INPUT element, type=”file”. The webbrowser will take care about URL encoding automatically.