PHP programs run on Web servers. They can work with database servers. PHP can also send email, read and write files, and interact with many kinds of other servers.

This short chapter is about how you’ll do PHP work. First, it reviews what PHP does. Then it recommends some tools to make your PHP work easier.

We’ve talked about the layers. On the previous page, we looked at HTML, the main technology of the display layers on the Web.

Let’s put the last three pages together. We’ll track a browser’s request for a page through to the server, and see the server’s response.