Variables are named containers that can store data (for example, a number, a text string or an object). Every variable - local or global - has a unique name of your choosing, however, there are rules you must follow when choosing these names. This resource will run through the ins and outs of all of these so that you can effectively make use of these elements in your web development work.

A media query is a logical expression that is either true or false. A media query is true if the media type of the media query matches the media type of the device, such as handheld, projection, or tv. These take into account aspect ratio, device height and width, orientation and resolution and more. Learning these tricks is essential to developing to multiple devices.

The World Wide Web Consortium (W3C), the standards body responsible for developing web standards, offers and online validation tool you can use to validate your web content. The W3C Markup Validation Service enables you to validate an HTML document to ensure that it has been coded accurately. W3C also provides a tool to validate CSS. You can enter a URL or upload a file using the options provided to validate the CSS structure. If an error is encountered, the W3C tool will provide specific detail about the error, including the line numbers of the code so you can easily track it down and correct the issues.

The colors you use can greatly influence your visitors; for example, if you are running an eCommerce site, you want to use colors that entice your users to view your catalog and eventually purchase something. In addition to changing the background of your pages to a color other than white, you can change the color text links, including various properties of links such as the hover color. You can also set the background color of container elements (such as paragraphs, sections, block quotes, and table cells), and you can use colors to specify the borders around those elements.

Most fonts include special characters for European languages, such as the accented é in café. Special characters can be inserted at any point in an HTML document by using the appropriate codes. HTML uses a special code known as a character entity to represent special characters such as © and ®. The below table lists the most commonly used character entities, although HTML supports many more.

Let's learn about using CSS to control aspects of your entire web page rather than just individual pieces of text or graphics. It is important to understand four particular CSS properties individually. For adding space around elements: (1) margins, and (2) padding. For placing your elements in relationship to others: (3) align, and (4) float.

To work with the browser and documents, JavaScript uses the hierarchy of parent and child objects found within the DOM. These objects, which are organized into a treelike structure, represent all the content and components of a web document and the browser that renders it. The objects in the DOM have properties that describe the web browser or document, and methods, or built-in code that enables you to work with parts of the web browser or document.