The enctype attribute of the FORM element specifies the encoding type used when submitting form data to the server. The default value is "application/x-www-form-urlencoded".
However, this encoding is inefficient when sending large amounts of text, text containing non-ASCII characters, or binary data to the server.
When uploading files, the encoding type used should be "multipart/form-data", which can send both text data and binary data uploads.
The ENCTYPE attribute value of the <form> form on the Browser side is multipart/form-data, which tells us that the transmitted data must use the multimedia transmission protocol. Since multimedia transmits a large amount of data, it is stipulated that the uploaded file must be the post method, < The type attribute of input> must be file.