In the preceding section, you saw how to read data from a web server. Now we will show you how your programs can send data back to a web server and to programs that the web server invokes.
To send information from a web browser to the web server, a user fills out a form, like the one in Figure 3.8.
When the user clicks the Submit button, the text in the text fields and the settings of the checkboxes and radio buttons are sent back to the web server. The web server invokes a program that processes the user input.
Many technologies enable web servers to invoke programs. Among the best known ones ...