Valid XHTML

HTML is a mark-up language used to create websites, and is independent of platforms.

"HTML is not a programming language, since HTML does not allow to, say, control a robot, set a variable or programme a game." (Quelle)

The display of invalid or incorrect documents depends on the software reading them (browser, roboter, screenreader, etc; see above). However, the display will vary greatly depending on the software, and this can lead to errors, often without the knowledge of the website manager, since it is impossible to test the website against all updates of all the software.

Non validated HTML source text can cause high costs, especially if it causes the software to look for an error or if the functionality and therefore the user experience is impacted.  


Further information:
The validity of the HTML source text can be checked with a so-called 'validator'.

Examples:

• http://validator.w3.org/ (a page of a web site)
• Qualidator SiteAnalyzer (all pages of a web site)

Further information
http://blog.antikoerperchen.de/beitrag/28/validierung-wozu-warum-valider-html-code-wichtig-ist.html

Acronyms: 
HTML: HyperText Markup Language

Complex URLs

"Even though machine-level addressing like the URL should never have been exposed in the user interface, it is there and we have found that users actually try to decode the URLs of pages to infer the structure of web sites. Users do this because of the horrifying lack of support for navigation and sense of location in current web browsers. Thus, a URL should contain human-readable directory and file names that reflect the nature of the information space."

Source:
http://www.useit.com/alertbox/9605a.html

Further information:
http://www.w3.org/QA/Tips/uri-choose

*** Members only ***

This test result is available for registered users and Premium Members.
More than two thirds of the test results will be available to you once registration has been successfully completed.

To have full access to the test results, and to be notified about changes in quality of the observed website, please register and upgrade to Premium Membership.

Register now free of charge

Image with Missing Width or Height

Missing height and width size of images is a typical error in HTML, which impacts the performance of the website. A precise definition of height and width allows a quicker download of the website, as the browser recognises the space needed for the image and can leave it empty.

Source and further information: http://de.selfhtml.org/html/grafiken/einbinden.htm#breite_hoehe