Quick Start with HTML - 2.6.2 Text Structures (Page 6 of 6 )
It's not obvious in our simple example, but the common carriage returns we use to separate paragraphs in our source document have no meaning in HTML or XHTML, except in special circumstances. You could have typed the document onto a single line in your text editor, and it would still appear the same in Figure 2-1.*
You'd soon discover, too, if you hadn't read it here first, that except in special cases, browsers typically ignore leading and trailing spaces, and sometimes more than a few in between. (If you look closely at the source example, the line "Greetings from" looks like it should be indented by leading spaces, but it isn't in Figure 2-1.)
22.214.171.124 Divisions, paragraphs, and line breaks
A browser takes the text in the body of your document and "flows" it onto the computer screen, disregarding any common carriage-return or line-feed characters in the source. The browser fills as much of each line of the display window as possible, beginning flush against the left margin, before stopping after the rightmost word and moving on to the next line. Resize the browser window, and the text reflows to fill the new space, indicating HTMLs inherent flexibility.
Of course, readers would rebel if your text just ran on and on, so HTML and XHTML provide both explicit and implicit ways to control the basic structure of your document. The most rudimentary and common ways are with the division (<div>), paragraph (<p>), and line-break (<br>) tags. All break the text flow, which consequently restarts on a new line. The differences are that the <div> and <p> tags define an elemental region of the document and text, respectively, the contents of which you may specially align within the browser window, apply text styles to, and alter with other block-related features.
Without special alignment attributes, the <div> and <br> tags simply break a line of text and place subsequent characters on the next line. The <p> tag adds more vertical space after the line break than either the <div> or <br> tag. [<div>, 4.1.1] [<p>, 4.1.2] [<br>, 4.6.1]
By the way, the HTML standard includes end tags for the paragraph and division tags, but not for the line-break tag.* Few authors ever include the paragraph end tag in their documents; the browser usually can figure out where one paragraph ends and another begins. Give yourself a star if you knew that </p> even exists.
Besides breaking your text into divisions and paragraphs, you can also organize your documents into sections with headings. Just as they do on this and other pages in this printed book, headings not only divide and entitle discrete passages of text, but they also convey meaning visually. And headings readily lend themselves to machine-automated processing of your documents.
There are six heading tags, <h1> through <h6>, with corresponding end tags. Typically, the browser displays their contents in, respectively, very large to very small font sizes, and usually in boldface. The text inside the <h4> tag typically is the same size as the regular text. [Heading Tags, 4.2.1]
The heading tags also break the current text flow, standing alone on lines and separated from surrounding text, even though there aren't any explicit paragraph or line-break tags before or after a heading.
126.96.36.199 Horizontal rules
Besides headings, HTML and XHTML provide horizontal rule lines that help delineate and separate the sections of your document.
When the browser encounters an <hr> tag in your document, it breaks the flow of text and draws a line across the display window on a new line. The flow of text resumes immediately below the rule.* [<hr>, 5.1.1]
188.8.131.52 Preformatted text
Occasionally, you'll want the browser to display a block of text as is: for example, with indented lines and vertically aligned letters or numbers that don't change even though the browser window might get resized. The <pre> tag rises to those occasions. All text up to the closing </pre> end tag appears in the browser window exactly as you type it, including carriage returns, line feeds, and leading, trailing, and intervening spaces. Although very useful for tables and forms, <pre> text looks pretty dull; the popular browsers render the block in a monospace typeface. [<pre>, 4.6.5]
Please check back next week for the conclusion to this article.
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