If you are looking for free resources to learn Ajax, PHP, CSS and JavaScript take a look at this collection with six interesting online presentations about these topics. The list includes a short introduction to Ajax, how to write modular CSS code, PHP Object Model fundamentals and an overview about the most popular JavaScript libraries.


1. Ajax 101 | Workshop
Author: Bill Scott | This presentation on SlideShare
Introduction to programming with Ajax. Covers XMLHttpRequest, XML, JSON, JavaScript, HTML, CSS, Dom Scripting, Event Handling with some examples from YUI library.


2. Modular CSS
Author: Russ Weakley | This presentation on Slide Share
A clearly explained modular system that allows you to hide and show CSS rules to specific browsers without the need for extensive hacks or workarounds.


3. Understanding the PHP Object Model
Author: Sebastian Bergmann | This presentation on SlideShare
This talk will give an overview of PHP's object model, covering both basic OOP concepts such as interfaces, classes, and objects as well as PHP's “magic” interceptor methods.


5. jQuery in 15 minutes
Author: Simon | This presentation on SlideShare
A short introduction to jQuery in particular about functions, collections, grabbing values and chaining.


6. JavaScript Library Overview
Author: Jeresig | This presentation on SlideShare
An interesting Overview about the most popular JavaScript libraries (jquery, prototype, Scriptaculous...) for web designers.