Web Design in a Nutshell, 3rd Edition

Information Browsers Ignore

Some information in an HTML document, including certain markup, is ignored or has little to no impact on presentation when the document is viewed in a browser or other user agent. These include:

Line breaks

Line returns in the HTML document are treated as spaces, which then typically collapse with other spaces (see next point). Text and elements wrap continuously until they encounter a p or br element within the flow of the document text. Line breaks are displayed, however, when text is marked up as a preformatted (pre) element or styled with the white-space: pre property in a style sheet.

Tabs and multiple spaces

When a user agent encounters more than one consecutive blank character space in an HTML document, it displays it as a single space. So, if the document contains:

far,            far                away

the browser displays:

far, far away

Extra spaces can be added within the flow of text by using the non-breaking space character entity ( ). Multiple spaces are displayed, however, when text is marked up as preformatted text (pre) or with the white-space: pre property in a style sheet. Tabs in the source document are problematic for some browsers and are best avoided.

Empty p elements

Empty paragraph elements (<p>...</p> or <p> alone) with no intervening text are interpreted as redundant by all browsers and displayed as though they were only a single paragraph break. Most browsers display multiple br elements as multiple line breaks.

Unrecognized element

A browser simply ...