# Entry Level PHP Web Application Development

This is an entry-level introduction to writing web applications in the PHP programming language. It focuses in providing the reader with all of the information that they need to know to get started with web development, without covering “advanced” programming concepts. This book is not a reference work: it is intended to teach web application development, as well as PHP, to the reader.
This book covers PHP 5, and makes use of the features of PHP 5 that are not present in previous major releases of PHP, such as PHP 3 or 4. PHP 5 has been out for long enough that nearly every serious hosting provider should have made the upgrade to it by this point in time. PHP 5 has features that simplify the development process for web applications, and it is recommended.
This book makes use of information in Wikipedia as well as on the Internet. As much neutral, objective information as possible is used to allow the reader to perform their own independent research and learning outside of the text of this book as necessary or desired. The goal of this book is to be an extremely high-quality work and to stand on as much pre-published information as available. Citations of, and references to other works should be considered to be normal, and encouraged.

### To readers new to Wikibooks

There is no “Errata” document published for this book. This book is an evolving work, and any errors are likely to be fixed when pointed out or otherwise found. If there is a possible error to investigate, use the discussion link at the top of the page with questionable information so that it can be investigated. If any information in this book contradicts official documentation or specifications, the reader may make the assumption that the official documentation is correct, unless there is documented, verifiable proof to the contrary.

## Structure of This Book

This book is structured to be read from “front” to “back” — from top to bottom in the Table of Contents. This book attempts to build on previously presented topics, so as to allow for logical presentation of content. There are also tasks for the reader to work on, presented throughout the text of the book, with probable solutions presented in appendices to the book. The reader is encouraged to work on the examples, and then compare what they have come up with to what is presented by the book.

## Programming Examples

It should go without saying that programming examples included with this book are released under the GNU Free Documentation License. Each example is intended to stand independently to demonstrate the immediate concept at hand, and examples should be heavily commented (more than “usual” code) to illustrate the how and why things are done.
Examples should also be tested, and cleanly work when copied and pasted for use. No warnings should be emitted, and examples should be kept up-to-date with current best practices and stadards, when possible. Any depreciated code should be clearly marked as such, when demonstrating historical methods.

## Prior Experience

The reader is assumed to have no prior experience with writing programs in any language. This is an entry-level work, and so it is intended to be more verbose with regard to the basics than an intermediate or advanced level text on web application programming.

## Covered Topics

This book covers all of the topics that are necessary for entry-level web application programming. There is information on the following subjects within this book:
* HTML
* XHTML (At this time, cursory; this book uses HTML 4.01 throughout, due to issues with XHTML proper and Microsoft Internet Explorer.)
* CSS
* JavaScript
* PHP 5 (PHP Manual)
* And more.

## Table of Contents

* What is Programming? Why Write for the Web?
* PHP Web Application Development Environments
* Our First Programs: Hello, World!
* HTML and CSS: Presentation to the User
* PHP: Performing (Relatively) Simple IO (Input-Output)