Programming PHP, 4th Edition

Chapter 1. Introduction to PHP

PHP is a simple yet powerful language designed for creating HTML content. This chapter covers essential background on the PHP language. It describes the nature and history of PHP, which platforms it runs on, and how to configure it. This chapter ends by showing you PHP in action, with a quick walkthrough of several PHP programs that illustrate common tasks, such as processing form data, interacting with a database, and creating graphics.

What Does PHP Do?

PHP can be used in two primary ways:

Server-side scripting

PHP was originally designed to create dynamic web content, and it is still best suited for that task. To generate HTML, you need the PHP parser and a web server through which to send the coded document files. PHP has also become popular for generating dynamic content via database connections, XML documents, graphics, PDF files, and so much more.

Command-line scripting

PHP can run scripts from the command line, much like Perl, awk, or the Unix shell. You might use the command-line scripts for system administration tasks, such as backup and log parsing; even some CRON job–type scripts can be done this way (as nonvisual PHP tasks).

In this book, however, we concentrate on the first item: using PHP to develop dynamic web content.

PHP runs on all major operating systems, from Unix variants (including Linux, FreeBSD, Ubuntu, Debian, and Solaris) to Windows and macOS. It can be used with all leading web servers, including the Apache, Nginx, ...