So, now we are ready to use PHP to write web programs, run and test them locally, and place them on a server that your web hosting company manages; in brief—to develop and deploy.

We focus on the use of PHP to generate web pages dynamically. After the PHP code is interpreted, what remains is HTML, which you should think of as strings of text that are generated on the server and rendered by the client. The data that is used to generate these pages either comes out of an external file or a database.

When invited to, the visitor of your site will interact with it. There may be a form to fill out, a button to click, a selection to be made out of several choices, and so on. The result of that intervention by the visitor needs to somehow make its way back to the server and be processed there, and all can be thought of as strings of text again. After processing, it either goes back to the client to inform the visitor and/or it needs to be stored somewhere. That somewhere...