Web Design Basics

With just a little extra mark-up you can greatly enhance your overall web design accessibility. Images are best with alt and pretty much everything can have a title. Add longdesc to important images to provide supplemental information. Don't use images to advertise vital information. Never ever use frames and try to avoid tables.

When defining fonts you really ought to bear in mind that Arial actually means Arial and not Tahoma, Verdana, or any other variant. Prefer dynamic units over static ones to set font-size and avoid values below 65%. You should always prefer recognised values of the 216 CLUT when defining colours.

Robots

Robots are automatic data harvesters. The specific rights for any given robot are configured in the special robots.txt file. However, bear in mind that their is no standard behaviour and most rogue bots ignore the file! You should always add a trailing slash to folder links to prevent extra redirects. Also please note that there is no Allow rule, simply because that is the default. See below for an example how to disallow the foo-bot from accessing /foo-dir and the blah-bot from accessing /blah. Use Disallow: /dir rather than Disallow: /dir/* and one path per line.

META Tags

META tags are becoming increasingly obsolete. You should aim to set most values of importance either in the server's main configuration or via .htaccess tweaks. Using HTTP headers is preferable over META tags.

META http-equiv

<meta http-equiv="content-type" content="text/html; charset=UTF-8">

Sets the document default content type. The HTTP content type may extend to the character set.

<meta http-equiv="content-language" content="en-GB">

Sets the natural language of the document. May be used by robots to categorise by language.

<meta http-equiv="content-script-type" content="text/javascript">

Sets the default scripting language of the document.

<meta http-equiv="content-style-type" content="text/css">

Sets the default style sheet language.

<meta http-equiv="expires" content="Wed, 26 Feb 1997 08:21:57 GMT">

Sets date and time after which the document should be considered expired and controls caching in HTTP/1.0. An illegal value like 0 is interpreted as immediately. A value of zero (0) may thus be used to force a modification check (reload) at each visit. Robots may delete expired documents from a search engine or schedule a revisit.

<meta http-equiv="pragma" content="no-cache">

Controls caching in HTTP/1.0. Value must be no-cache.

<meta http-equiv="refresh" content="3;url=http://www.abc.xyz/123.html">

Sets delay in seconds before the document is automatically re-loaded and optionally specifies an alternate URL to load.

<meta http-equiv="vary" content="content-language">

Specifies available alternates. If a header accept-language is sent, an alternate form may be selected.

<meta http-equiv="window-target" content="_top">

Sets the named window of the current page. May be used to stop a document from appearing in a frame.

META name

<meta name="description" content="Joes Supa Dupa Office Tools">

Plain text document information.

<meta name="keywords" content="Joes Supa Dupa Office Tools">

Index a document with Search Engines.

<meta name="language" content="en-GB">

Similar to http-equiv content-language. Seems more reliable if applied via meta name rather then meta http-equiv.

<meta name="robots" content="noindex, follow">

Controls robots behaviours on a per-page basis. Meaningful values are noindex, nofollow, noodp, and noydir.

<meta name="author" content="Joe Doe">

Typically unqualified author's name.

<meta name="copyright" content="Joes Supa Dupa Office Tools">

Unqualified copyright statement.

MIME Types

MIME types are the technical definition for a given resource. Visit the IANA MIME types page for a more complete listing.

Browser Safe Colours

The browser safe colours look-up table represents the colours presumably rendering equal across all major platforms.

216 CLUT browser safe colours look-up table