HTML

html enctype

<form action="/action.php" method="post" enctype="multipart/form-data">
  ...
</form>

<!-- 
    Attribute Values
    1. application/x-www-form-urlencoded	
    2. multipart/form-data	
    3. text/plain	
-->

enctype

multipart/form-data	 This value is necessary if the user will upload a file through the form