1. Introduction
  2. History
  3. Web Standards
  4. Structure and presentation
  5. (X)HTML
  6. CSS
  7. Accessibility
  8. URLs
  9. References
  10. Glossary

3. Web standards

What are web standards?

Web standards are technologies, established by the W3C and other standards bodies, that are used to create and interpret web-based content. These technologies are designed to future-proof documents published on the Web and to make those documents accessible to as many people and devices as possible.

Structural languages

Presentation languages

Object Models

Scripting languages

This document focuses on HTML 4.01 Strict for structure, CSS Level 1 and Level 2 for presentation, and JavaScript for scripting (not that there are a lot of scripting examples).

When a document is said to adhere to web standards, it means that the document, besides using the above technologies:

Note that “works in any web browser” does not mean “looks the same in every web browser”. Making a document look identical across browsers and platforms is next to impossible. Not even using only images will make a website look exactly the same everywhere.

Documents that are published on the web will be accessed by a wide variety of browsing devices on several operating systems, with monitors of differing size and quality (or no monitor at all), by users who may have changed their browser’s default text size and other preferences.

Realising this and accepting that you simply cannot fully control the visual appearance of a website in your visitors’ browsers will make your life a lot less frustrating. Anyone who creates websites needs to understand that there are technical prerequisites to consider, the same way as those who publish on paper or make movies or television have other prerequisites to consider.

Do websites need to look exactly the same in every browser?

Why use web standards?

Some web developers and web designers have a resistance towards using web standards. Common arguments are It’s too difficult, It works anyway, and The tools I use create invalid code.

It’s easy to react emotionally and build up a resistance towards learning something new and abandoning techniques you know and feel comfortable with. However, if you look at the situation logically you will see that there are many benefits to learning and using web standards. Here are a few:

Using web standards saves time and money for website creators and in general provides a better experience to the website’s visitors.


Validation is the process of controlling that a document adheres to the rules of the programming language used in the document. You can compare it to checking a text you have written for spelling errors.

Quality assurance through validation is an important part of web development. Many errors that are hard to spot manually are discovered during validation. An error can be as trivial as a typo or as serious as an element or attribute being used in an invalid way. It can also have absolutely no effect on the way the document is rendered in a web browser or completely mess it up.

Unfortunately, many people don’t validate their documents. Some people may not know about validation, others forget to validate, and there are those who intentionally avoid validating. I think this situation can largely be blamed on web browser vendors. Most web browsers attempt to interpret invalid HTML as best they can and try to guess what the author’s intention is instead of displaying an error message. It is understandable that web browsers want to do that, but this error tolerance is undoubtedly one major reason for the sloppy markup that is very common today.

Why we won’t help you is Mark Pilgrim’s excellent explanation of the advantages of validation. The article also explains why it may be harder to get help from people on discussion forums and mailing lists if you haven’t validated your documents before asking for help.

Some HTML editors have built-in validation tools or will use the W3C’s validation services, available online. You can also use the W3C’s validation services manually:

Another excellent tool for checking the validity of the HTML you create is the HTML Validator extension for Firefox.

Understanding the error messages generated by the validators can be a little tricky. An error early on in a document may cause several additional errors. By fixing the first error and revalidating you will often greatly reduce the number of errors.

It is important to realise that validity alone does not mean that your document is accessible. Neither do a few validation errors necessarily make your document inaccessible or incompatible. That said, you should always aim for fully valid code and have a very good reason (such as improving accessibility for people with disabilities) for any errors you decide to leave in. If the tools (code editors, frameworks, WYSIWYG editors, content management systems) you use generate invalid markup, those tools are broken and need to be fixed.

Further reading

Comments, questions or suggestions? Please let me know.

© Copyright Roger Johansson