The input form

We'll need a pair of files: the original HTML file that presents a form to fill in with input values, and a Python program that processes the form values and returns some output. Here's our input form respond.html:

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <title>Input form for respond.py</title>
</head>
 
<body>
<h2>Input form for respond.py</h2>

  <form method="post" action="cgi-bin/respond.py">
    <p>Enter your name: <input type="text" name="user" /></p>
    <p><input type="submit" /></p>
  </form>

</body>
</html>

Viewed in the browser it will look something like this,

Everything is set up by the lines of the form element:

<form method="post" action="cgi-bin/respond.py">

This line says that when the Submit button is clicked the form data should be sent to the program cgi-bin/respond.py on the server.

    <p>Enter your name: <input type="text" name="user" />

This line gives a name to the contents of the input box. Within our program we will be able to identify it by the index "user".

    <p><input type="submit" /></p>

This line places the Submit button on the screen. Nothing is sent to the server until this button is clicked, but as soon as it is clicked the form contents are encoded and forwarded to the server. The Submit button is the GUI counterpart to pressing the Enter key in the IDLE shell.