1. Why use Web Standards?

2. The Three Layers of the Web

3. 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.

4. What are Web Standards?
When the Internet and the Web became mainstream in the second half of the nineties, web browser vendors had not yet implemented CSS (Cascading Style Sheets) well enough for web developers to be able to use it to control the presentation of an HTML document.

5. What are Web Standards?
The lack of implementation is partly understandable considering that the specification for CSS Level 1 was published in 1996 and the specification for CSS Level 2 in 1998.

6. What are Web Standards?
The lack of CSS support in web browsers, combined with demands from graphic designers used to the level of control that is possible when working with printed material, led to the abuse of HTML in any way possible to control the visual presentation of a web page.

7. What are Web Standards?
One example of this is the major “breakthrough” that was made when designers discovered that by using the attribute border=“0" to hide the borders of an HTML table, an invisible grid that could be used to control layout was created. Another example is the use of transparent, and thus invisible, images called “spacer GIFs” to control spacing and margins.

8. What are Web Standards?
Since HTML was never meant to be used to control the presentation of a document, hacks, invalid code, and vendor-specific elements and attributes were (and still are) used.
Validation was something that very few knew about or used.

9. What are Web Standards?
As new versions of web browsers were released, CSS support was improved and extended, but not at the rate it should have been.

10. What are Web Standards?
However, there is no longer any reason not to use HTML the way it was meant to be - to describe the structure and content of a document and not its presentation. For that, we can now use CSS, which was designed specifically for that purpose.

11. Structural languages HTML (Hypertext Markup Language) 4.01
XHTML (Extensible Hypertext Markup Language) 1.0
XHTML 1.1
HTML5
XML (Extensible Markup Language) 1.0

12. Presentation languages
CSS (Cascading Style Sheets) Level 1
CSS Level 2 revision 1
CSS Level 3 (in development)
MathML (Mathematical Markup Language)
SVG (Scalable Vector Graphics)

13. Object Models DOM (Document Object Model) Level 1 DOM Level 2
DOM Level 3 Core

14. Scripting languages
ECMAScript 262 (the standardised version of JavaScript)

15. What are Web Standards?
When a document is said to adhere to web standards, it means that the document besides using the above technologies:
Consists of valid HTML or XHTML
Uses CSS instead of tables for layout
Is properly structured and semantically marked up
Works in any web browser

16. What are Web Standards?
“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.

17. What are Web Standards?
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.

18. 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”.

19. Why use Web Standards?
Simpler development and maintenance: Using more semantic and structured HTML makes it much easier and quicker to understand code created by somebody else.
Compatibility with future web browsers: When you use defined standards and valid code you future-proof your documents by reducing the risk of future web browsers not being able to understand the code you have used.

20. Why use Web Standards?
Faster download and rendering of web pages: Using CSS for presentation tends to make HTML documents leaner which means quicker downloads for your visitors.
Better accessibility: Semantic HTML, where structure is separated from presentation, makes it easier for screen readers and alternative browsing devices to correctly interpret the content.

21. Why use Web Standards?
Better search engine rankings: The separation of content and presentation makes the content represent a larger part of the total file size. Combined with semantic markup this generally improves search engine rankings.

22. Why use Web Standards?
Simpler adaptation: A semantically marked up document can be easily adapted to print and alternative browsing devices, like handheld computers and mobile phones, just by linking to a different CSS file. You can also make site-wide changes to presentation by editing a single file.

23. W3C HTML Specifications and Timeline
Recommendation
HTML 3.2
14. January 1997
HTML 4.0
24. April 1998
HTML 4.01
24. December 1999
HTML 5
19. October 2010 (latest draft)

24. W3C XHTML Activities
XHTML is a stricter and cleaner version of HTML.

25. XHTML Versions – 1.0
XHTML 1.0
XHTML 1.0 became a W3C Recommendation 20. January 2000. 
XHTML 1.0 Second Edition
XHTML 1.0 Second Edition became a W3C Recommendation 1. August The second edition was not a new version, but an update and a "bug-fix".

26. About XHTML 1.0
XHTML 1.0 was the first major change to HTML since 1997.
XHTML was an important step for creating a standard that provided richer web pages on a wider range of user agents (browsers), like desktop PCs, mobile (wireless) devices, and cell phones.

27. About XHTML 1.0
XHTML 1.0 reformulates HTML 4.01 in XML. XHTML 1.0 relies on HTML 4.01 for the meanings of the HTML tags.
W3C's next step included modularization of XHTML into smaller element collections, to make it easier to combine XHTML with other markup languages, like vector graphics or multimedia. 

28. About XHTML 1.0
Modularization of XHTML reduced development costs, improved cooperation with other applications (like databases), easier communication with different user agents, and cleaner integration between HTML and different XML standards.

29. W3C XHTML Activities - XHTML 1.0
XHTML 1.0 is a reformulation of HTML 4.01 in XML.

30. W3C CSS Activities
CSS defines HOW HTML elements are to be displayed.

31. CSS Versions CSS1 CSS1 became a W3C Recommendation 17. December 1996.
CSS2 became a W3C Recommendation 11. January CSS2 has added support for media (printers and aural devices), downloadable fonts, element-positioning and tables.

32. CSS Versions
CSS3
CSS3 is about breaking CSS into smaller modules.

33. W3C XML Specifications and Timeline
Draft/Proposal
Recommendation
CSS 1
17. Dec 1996
CSS 1 (Revised)
11. Apr 2008
CSS 2
12. May 1998
CSS 2.1
08. Sep 2009
CSS Mobile Profile 2.0
10. Dec 2008
CSS TV Profile 1.0
14. May 2003
CSS Print Profile
13. Oct 2006

34. W3C XML Specifications and Timeline
Draft/Proposal
Recommendation
CSS 3
23. May 2001
CSS 3 Namespace
23. May 2008
CSS 3 User Interface
11. May 2004
CSS 3 Selectors
10. Mar 2009
CSS3 Fonts
18. Jun 2009
CSS3 Colors
21. Jul 2008
CSS 3 TV
14. May 2003
CSS 3 Backgrounds and borders
10. Sep 2008

35. W3C XML Specifications and Timeline
Draft/Proposal
Recommendation
CSS 3 Text
06. Mar 2007
CSS 3 Lists
07. Nov 2002
CSS 3 Line
15. May 2002
CSS 3 Box model
09. Aug 2007
CSS3 Multi column
30. Jun 2009
CSS3 Ruby
14. May 2003
CSS 3 Speech
16. Dec 2004

36. W3C XML Specifications and Timeline
Draft/Proposal
Recommendation
CSS 3 Paged Media (PM)
10. Oct 2006
CSS 3 Generated PM
04. May 2007
CSS 3 Print
13. Oct 2006
CSS 3 Values
19. Sep 2006
CSS3 Cascade
15. Dec 2005
CSS3 Template Layout
02. Apr 2009
CSS 3 Media Queries
15. Sep 2009