emphasize standards compliance. By complying with existing standards, rather than relying upon browser specific extensions, you can make sure that the web sites you design will be readable by all browsers supporting those standards, not just the ones you have time to test it on, and that your page designs won't break when new browsers and versions come into existence. HTML tags that go through the standards process are evaluated more thoroughly and designed for graceful degradation on older browsers.

The World Wide Web Consortium (W3C) is the focal point for web standards- see their pages (and some other useful resources) for more details:

1. http://www.w3.org/
W3C - The World Wide Web Consortium (Information on current and proposed HTML specifications)

2. http://www.w3.org/MarkUp/html-spec/
HTML 2.0

3. http://www.w3.org/MarkUp/Wilbur/
HTML 3.2

4. http://www.w3.org/TR/REC-html40/
HTML 4.0

5. http://www.htmlhelp.com/design/standards.html
Web Design Group - Standards for HTML Authoring for the World Wide Web
The WDVL: HTML Standards Compliance - Why Bother?

When writing to an HTML standard, make sure to use the one most appropriate to your needs. If you don't need any extended features, or expect to have a lot of visitors with very old browsers, you may want to follow HTML 2.0 compliance. Most currently updated browsers have support for HTML 3.2, so it is generally the best to use if you want to use features not in HTML 2.0 (don't forget to plan for graceful degradation - see "Graceful Degradation" section below). If you need some of the newest features of HTML, like frames, HTML 4.0 is what you should use, but remember that most browsers do not support most of the new features included in HTML 4.0 yet, and you should setup your pages to degrade gracefully.

Accessible Design Tools
===============
It is almost always best to use a text-based editor rather than a graphical editor. There are cases in which a graphical editor may be necessary, but if you can use a text-based editor, you have a lot more control over the accessibility of your site.

Graphical Tools
------------------
Choose an editor which doesn't rewrite your code without your permission (FrontPage for example is a major culprit for this), that creates pages based on standards (and preferably allows you to specify which standards you are targetting), and that allows you to take advantage of the standard accessibility features of HTML, such as ALT and NOFRAMES.

Make sure to run your pages through a validator (see, "Web Site Testing" section below) at least the first times even if the program has a built in checker, since the checker that is built in may not be thorough, and you can't really tell without running a comparison check. Also, I recommend against using the graphical editors distributed by the major browser vendors (Netscape's Composer and Microsoft's FrontPage) as they tend to have a bias towards coding for their own browser. If you can give me some information on which tools are good and which should be avoided, please let me know. If you must use a graphical editor which produces poor HTML, it is highly recommended to use HTML Tidy to clean it up before posting or editing it by hand.

* Amaya (W3C, Windows and Unix)
"Amaya is the name of W3C's own test-bed browser/authoring tool and is used to demonstrate and test many of the new developments in Web protocols and data formats. Given the very fast moving nature of Web technology, Amaya has a central role to play. It is versatile and extensible - new features can be easily added - and is available on both Unix and Windows '95/NT platforms. Amaya is a complete web browsing and authoring environment and comes equipped with a WYSIWYG style of interface, similar to that of the most popular commercial browsers. With such an interface, users do not need to know the HTML or CSS languages."

* Adobe GoLive (Adobe/GoLive, Mac and Windows)
Adobe GoLive is a complete web design tool and site management package. Some of the features which make it useful for accessible site design are: the ability to target for specified HTML or browser versions, the fairly clean and valid code it generally produces, the HTML checker, the included scripts (for Javascript and DHTML) which are designed to degrade appropriately and work in multiple browser versions, and the quality text editor included (and the ability to also work in the editor of your choice).

* Macromedia Dreamweaver (Macromedia, Mac and Windows)
Dreamweaver is a graphical editor which also includes site management features, and first class text editors (HomeSite/BBEdit) appropriate for each platform it's available for. It won't change your HTML unless you ask it to.

Text-Based Tools
-------------------
Text-based editors are best for making accessible sites, because they give you more control over the code they use. In a text-based editor, a web site is as accessible as you make it. Some editors provide functionality which make it easier to produce or test for accessibility. Here are a few.

* BBEdit (Bare Bones Software, MacOS)
BBEdit is a basic text editor with powerful features and a full suite of HTML tools. It has a robust plug-in architecture, with many useful web design plugins available, multi-file search and replace (with regular expression support), and many other useful features. The lite version is free, the pro version comes with more useful plugins, an HTML checker, link checker, HTML aware spell checker, and other useful features.

* HotDog (Sausage Software, Windows, description courtesy of Sausage Software)
As you type, HotDog provides continual feedback on the HTML code you are using. This feedback takes the form of tool tips which explain what each tag and attribute does.

Unfortunately the several different browsers on the market each conform to different HTML standards. While all browsers support the bulk of the HTML language, they all add extra functionality of their own. For example, Netscape has Netscape Extensions and Microsoft have their own extensions as well.

A professional web designer has to make sure their web page looks great under any browser. The only way they can insure this is by knowing which browsers support the different tags and attributes they are using. HotDog has many ways of giving the user this information on the fly. Holding down the CTRL key and moving the mouse over any tag or attribute reveals for what HTML specification the tag or attribute is defined.

A key part of HotDog's ability to provide this syntax information to users is the HTML Property Sheet. The HTML Property Sheet is a panel that sits next your document in HotDog. This panel lists all the known attributes for the tag you are editing. This list of attributes is usually ordered by what browsers support them.

For example, as soon as you type <TABLE> in HotDog, the HTML Property Sheets has listed all the attributes that can be used with the Table tag, and it has listed the attributes by which browsers support them. This enables professional web designers to make informed choices about the HTML they are creating.

The Syntax Manager can be told to only recognize any HTML specification you choose, in particular, the HTML 3.2 specification which nearly all browsers support in its entirety. By using the HTML 3.2 specification only you can be sure your are using HTML code that any browser can display. This would mean that as soon as type a tag or attribute that is not part of the HTML 3.2 specification, it would be colored red to indicate that it might not be recognized by some browsers.

* HomeSite (Allaire Corp., Windows)
HomeSite is a full fledged web design tool with many useful features, including web page validation.

* NoteTab (Fookes Software, Windows)
NoteTab Pro is a leading-edge text editor and HTML coding tool, and an ideal Notepad replacement. Winner of top shareware industry awards since 1998, this elegant application does it all: you can handle multiple large files with a simple tabbed interface, use a spell-checker and thesaurus, format text, use multiple undo, and bookmark documents. You can build templates, use powerful system-wide searches, and do global multi-line replacements.

Its Clipbook feature lets you create and organize clips, which can range from text macros to complete mini-applications, using a simple scripting language with enough features to satisfy any power user; a bunch of handy clip libraries is included.

Web authors will love the HTML clip library, just one of a load of features that make NoteTab a great code-based HTML editor. Other features include text-to-HTML conversion, tag stripping, and tools for adding links and color codes.

* Arachnophilia (Windows, Java)
Arachnophilia's purpose is to create Web pages. It does this in one of two general ways. The easy way is to drop a Rich Text Format (RTF) document onto the Arachnophilia program window and watch Arachnophilia turn it into a web page for you. The not so easy way is to write the HTML code yourself, which, although more work, produces the most professional-looking results. Arachnophilia will help you create Web pages, no matter what method you choose. And, by just typing, you can create new Arachnophilia commands, even entire toolbars, for HTML tags the author hasn't thought of -- Arachnophilia's suite of commands is entirely under your control. You can load hundreds of documents at once (memory permitting) and search through them at once for particular words. You can preview your work on up to six browsers, thus assuring your pages will look good no matter what browser your visitors own.

Web Site Testing
============
Validators and linters are the two most common types of HTML testers. The main difference between a validator and a linter is that a validator checks a page against a published HTML specification for technical errors, whereas a linter checks a page for commonly made mistakes. It is often a good idea to use both as they can sometimes find different types of problems.

Validators and/or linters are included with a few good quality HTML editors, including Bare Bones Software's BBEdit Pro, Allaire's HomeSite, and Sausage Software's HotDog. If your software doesn't include a validator or at least some sort of HTML checker, it is a very good idea to find one to use. Don't assume that your editor creates valid code. This is very often not the case. Simply testing your pages in your favorite browser or even a couple browsers won't really tell you if you've got some sort of error in your pages that may not be corrected for in another browser, or in a new version of your current browser (i.e. Netscape 4 no longer allows you to forget ; in entities, like ©). There are a few validators and linters listed at Yahoo. In addition, here are a couple of the more useful web based ones:

- W3C Validation Service (HTML 4.0 validator provided by the HTML standards source)
- Weblint (a very popular Perl based linter, which can be downloaded for use on most platforms, and is used in tandem with web based validators)
- CSSCheck, a Cascading Style Sheets Lint
- Bobby (checks web pages for common accessibility problems)
- HTML Tidy (not really a checker- it will take a page, cleans up the bad HTML, and give you suggestions on how to improve page accessibility)

Graceful Degradation
==============
Since HTML is continually changing and different browsers support different elements, graceful degradation is the key to making sure that pages are readable and accessible in all browsers. When a browser encounters tags it doesn't understand or can't display, degradation takes place. Whether this degradation will cause some of your page content to be lost to the browser, or whether the content of your page can still be accessed fully is dependent on whether the degradation is graceful.

The HTML standards were written with graceful degradation in mind- new attributes to older tags are safely ignored so that the rest of the tag can still function normally, and new tags are written with alternative display for browsers that don't support them in mind. There are many elements of HTML that can't be displayed or can be turned off in browsers that were written with the knowledge of these elements- such as images, java, and frames. Using the appropriate methods to provide an alternative message to those who can't see those elements or have turned them off is one way to design for graceful degradation.

If you design pages with graceful degradation in mind, by utilizing the built in elements of the HTML standards, you can design pages that should degrade gracefully in all browsers and are accessible (see "Accessibility" section below).

Accessibility
========
In the context of web site design, accessibility is a measure of how easy it is to access, read, and understand the content of a web site. Accessibility is complicated by the fact that a web site is not a published piece of work so much as a living document that can be interpreted in different ways by different browsers and on different platforms. Web sites are not a print medium- although they are most often read in a visual manner, there are many different ways a web page can be experienced, such as via a speech browser or via an indexing robot. A web page is a combination of textual information which is interpreted appropriately by a browser and linked to files of various types, such as graphics, movie clips and sound files.

Since a web page can be interpreted differently by different browsers with different capabilites, and since the language of a web page- HTML, is constantly evolving, accessibility must be considered to make a page usable by as many people as possible. The keys to making your page accessible are graceful degradation, standards compliance, fast loading, and intelligent organization.