Graphics Programs Reference
In-Depth Information
Evolving HTML and CSS Standards
The way that HTML displays and formats text has evolved over time. Each evolutionary
step has provided better control over the way text is formatted and displayed.
Written Communication: W3C Recommended HTML Standards
The World Wide Web Consortium (W3C) publishes recommendations for HTML standards.
It is important to stay informed about changing standards because using old techniques
to code Web pages can prevent new browsers from displaying the content of your site cor-
rectly. This can prevent you from communicating effectively with your target audience. As
new versions of HTML are developed and then accepted, the W3C assigns version numbers
to these standards (a lower number equals an earlier standard). New HTML versions contain
new elements, tags, and updated methods of doing things. Tags that have been replaced
in new versions of HTML are kept around for compatibility with older browsers. Older tags
that are in the process of becoming obsolete are called
deprecated
. Because some people
use older browsers that rely on the earlier versions of HTML, deprecated tags are phased
out slowly. Specifications and standards change rapidly, so there is no easy way to predict
exact adoption rates for newer standards and technologies. The W3C Web site (
w3c.org
) is
a good reference for current trends and changes.
In the earliest days of the Web, designers had limited control over the way text was
displayed in a browser. Text appeared in the default font and size set by the user's
browser. The way it looked was also affected by the user's operating system. Designers
had no font control within a Web page except for the six predefi ned heading tags that
could be used to denote importance of text by changing the relative size of the head-
ings. In HTML 2, bold, italic, and underline attributes were added. In HTML 3.2, another
milestone in controlling the display of text was reached—the HTML font tag (or just font
tag). The
font tag
allowed designers to designate in which font and relative font size the
Web page should display (as long as the designated font was installed on the user's com-
puter). Font tags were deprecated in HTML 4.01, and their functions were replaced and
expanded upon by Cascading Style Sheets.
The current standard for creating Web pages is
Extensible Hypertext Markup Language
(XHTML)
, which is basically a combination of HTML and XML.
XML (Extensible Markup
Language)
is a markup language that describes the structure of the data it contains. It pro-
vides a common and fl exible method for applications and organizations to electronically
exchange information. XML was created to describe or identify data, whereas HTML was
designed to display data. The shift from HTML 4.01 to XHTML 1.0 continues the move
toward separating style and content—XHTML structures the page content and CSS styles
it for display. As an additional benefi t, XHMTL more strictly defi nes the syntax and makes
it easier to format the same content for display on various devices.
Exploring Cascading Style Sheets
Cascading Style Sheets were created as the answer to the limitations of HTML, and they
are the current standard for layout and formatting of Web pages. A
Cascading Style Sheet
(CSS)
is a collection of styles that is either inserted in the head of the HTML of a Web
page and used throughout that page (an internal style sheet), or is attached as an external
document and used throughout the entire Web site (an external style sheet). A
CSS style
is a rule that defi nes the appearance of an element in a Web page either by redefi ning
an existing HTML tag or by creating a custom style (also called a class style or a custom
class style). CSS styles defi ne the appearance and position of text and graphics, and con-
trol most aspects of Web page layout. They allow you to specify more parameters of the
design than earlier HTML specifi cations; for example, you can create custom list bullets.
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