In this chapter you have learned some incredibly important concepts. You learned what variables are, and how to create them in PHP. You've learned how to connect a form to a PHP program with modifications to the form's method and action attributes. You learned how to write normal links to send values to server-side scripts. You've built programs that respond to various kinds of input elements, including drop-down lists, radio buttons, and list boxes. You've gone through the process of writing a program from beginning to end, including the critical planning stage, creating a form for user input, and using that input to generate interesting output.