File Upload-upload files on the php page

Generally, when you Click Upload file on a php page, a browser box is displayed, and you can select File Upload to go to the server. I imagine a socket programming process: there is a local client, first open the local file, then read the file, and then use the socket to send the read content... generally, when you Click Upload file on a php page, a browser box is displayed, and you can select File Upload to go to the server.
I imagine a socket programming process: there is a local client, first open the local file, then read the file, and then use the socket to send the read content to the remote server, the server uses the socket, read the data and write it to the remote server.

So how does php Upload files? How can I upload a local file to the remote without a socket?

Reply content:

Generally, when you Click Upload file on a php page, a browser box is displayed, and you can select File Upload to go to the server.
I imagine a socket programming process: there is a local client, first open the local file, then read the file, and then use the socket to send the read content to the remote server, the server uses the socket, read the data and write it to the remote server.

So how does php Upload files? How can I upload a local file to the remote without a socket?

Generally, files are uploaded through form post. For details, refer to thinkphp.
Http://document.thinkphp1.cn/manual_3_2.html#template_layout

Post is http/tcp