Differences between multipart/form-data and application/X-WWW-form-urlencoded

In the form Element syntax, enctype indicates the format of the submitted data.

Use the enctype attribute to specify the encoding type used by the browser when data is sent back to the server.
Below is the description:
Application/X-WWW-form-urlencoded: Form data is encoded as name/value pairs. This is the standard encoding format.
Multipart/form-data: the form data is encoded as a message. Each control on the page corresponds to a part of the message.
Text/plain: the form data is encoded in plain text format, which does not contain any controls or format characters.
 

 
Supplement
 

  the enctype attribute of form is encoded in two ways:  application/X-WWW-form-urlencoded  and multipart/form-data. The default value is  application/X-WWW-form-urlencoded . 
 when the action is get, the browser uses the X-WWW-form-urlencoded encoding method to convert form data into a string (name1 = value1 & name2 = value2 ...), then append the string to the end of the URL, using? Load the new URL. 
 when the action is post, the browser encapsulates form data in the HTTP body and sends it to the server. 
 if no type = file control exists, use the default  application/X-WWW-form-urlencoded . 
 however, if type = file exists, multipart/form-data is required. The browser splits the entire form into controls and adds content-disposition (Form-data or file) and Content-Type (text/plain by default) to each part ), name (Control name) and other information, plus the delimiter