HTML and CSS Reference
This embedding code works on all modern browsers and validates as XHTML 1.0 Strict, XHTML 1.1, and HTML5.
There is just one issue with (X)HTML documents embedded with the object element: the layer order set by z-index
in the CSS is ignored by older versions of Internet Explorer.
Semantic Web Best Practices
The World Wide Web Consortium provides Semantic Web best practices on implementing RDF Schema and OWL,
and use them with object-oriented programming languages . Image Annotation on the Semantic Web  describes
the importance and advantages of image metadata, and provides guidelines for semantic image annotation and use
cases. Further documents on Linked Data and controlled vocabularies are the Best Practices for Publishing Linked
Data , the Linked Data Platform Best Practices and Guidelines , and the Best Practice Recipes for Publishing RDF
WAI-ARIA Best Practices
The W3C WAI-ARIA Authoring Practices Guide describes best practices for developing rich Internet applications .
Approaches are recommended to create accessible widgets, keyboard navigation, form properties, drag-and-drop
support, relationships, dialog boxes, and reusable component libraries.
Mobile Web Best Practices
More and more users browse the Internet on smartphones and tablets with smaller screen size, limited bandwidth,
and a less convenient interface than desktop computers. Mobile-optimized web pages should be designed and served
in the appropriate manner to provide a reasonable user experience. The specific features of mobile devices should be
taken into account when designing for mobile media . The most important considerations are as follows :
• Limited bandwidth : Techniques such as compression, caching, and minimized data size
can contribute to a better user experience for 3G and 4G mobile browsing 5 . Cookies and
redirections should be eliminated whenever possible.
• Limited processing capacity : A large DOM, huge background images, a large number of scripts,
and so on, can increase processing time. As a result, users will have to wait for relatively long
periods of time, which should be avoided. Simple markup can be provided for mobile devices
with XHTML Basic . As for styles, CSS has a profile dedicated to mobile devices . Note
that smartphone processors became very powerful in the early 2010s, featuring multi-core
architectures with a relatively high clock rate that do not have limited processing capacity
• Limited technology support : Do not rely on scripts, embedded objects, cookies, or style sheets.
Tabular presentation should be minimized. Since mobile browsers usually support a small
set of file types only, download sections should warn users of files provided in formats poorly
supported by mobile devices.
5 Smartphones are often connected to the Internet through WiFi unless the user is on the go.