HTML developer guide

Overviews

Forms in HTML

This article summarizes changes to HTML forms introduced in HTML5. For a detailed guide to using forms, see our extensive HTML forms guide.

HTML5

HTML5 is the latest evolution of the standard that defines HTML.

Sections and Outlines of an HTML5 Document

The HTML5 specification brings several new elements to web developers allowing them to describe the structure of a web document with standard semantics. This document describes these elements and how to use them to define the desired outline for any document.

Using HTML5 audio and video

HTML5 introduces built-in media support via the <audio> and <video> elements, offering the ability to easily embed media into HTML documents.

Guides

Introduction to HTML

This article provides an introduction to HTML. If you've ever wondered what goes on behind the scenes in your web browser, this article is the place to start learning.

Content Editable

Technical review completed.

Content categories

Each HTML element must abide by rules defining what kind of content it can have. These rules are grouped into content models common to several elements. Each HTML element belongs to zero, one, or multiple content models, each setting rules that the element's content must follow in an HTML-conformant document.

Drag Operations

The following describes the steps that occur during a drag and drop operation.

Dragging and Dropping Multiple Items

Mozilla supports the ability to drag multiple items using some additional non-standard methods. These are methods that mirror the types property as well as the getData(), setData() and clearData() methods, however, they take an additional argument that specifies the index of the item to retrieve, modify or remove.

Email links

It's often useful for Web sites to be able to create links or buttons that, when clicked, open a new outgoing email message. For example, this might be used when creating a "contact us" button. This is done using the <a> element and the mailto URL scheme.

Event attributes

Every HTML element has a set of attributes that allow for the execution of JavaScript when certain events happen. These attributes are called event attributes and are the name of the event prefixed by "on".

HTML forms guide

This guide is a series of articles that will help you master HTML forms.

Obsolete practices to avoid

This article tries to list older coding practices that over time have become unnecessary or bad practices.

Recommended Drag Types

HTML drag and drop supports dragging various types of data including plain text, URLs, HTML code, files etc. The document describes the best practices for dragging common data types.

The Importance of Correct HTML Commenting

When authoring HTML in standards mode, incorrectly formed comments can break your pages, resulting in part or all of your content being commented out. When authoring XHTML or XML, incorrect comments will result in your documents not being able to be displayed at all.

Tips for authoring fast-loading HTML pages

These tips are based upon common knowledge and experimentation.

Using data attributes

HTML5 is designed with extensibility in mind for data that should be associated with a particular element but need not have any defined meaning. data-* attributes allow us to store extra information on standard, semantic HTML elements without other hacks such as classList, non-standard attributes, extra properties on DOM, or setUserData.

Sample code

Other pages

Element

An element is a part of a Web page or document. In XML and HTML, an element might contain a data item or a piece of a Web page such as a chunk of text or an image. A typical element includes an opening tag, attributes, content and a closing tag.

Hyperlink

Hyperlinks connect Web pages, or data items, to one another. In HTML, anchor elements define the hyperlinks you see when you browse the Web. An anchor can create a link from a part of a Web page, such as a text string or image, to another site, page or even a particular point within a page.