When looking at a web document your first impression may be formed by a slick appearance, attractive lay-out and nice graphics. But the main criteria for judging the quality of a web document are accuracy, objectivity, authority and currency.
Accuracy
Do you have good reason to believe that the information on the site is accurate? Are the facts documented? Can the information be compared with other sources?
Is it clearly stated who wrote the information? Does the author provide an e-mail address? Can you verify somehow that the author is an expert on the subject?
On the Internet, nobody knows you're a dog. (Or so you think.)
Objectivity
What is the author's point of view? Is the information covered fact, opinion, or propaganda?
What is the purpose of the document and the site on which it was published? Is this page a mask for advertising?
Who is sponsoring this site? Sponsorship can affect content and objectivity.
In short: why was this written and for whom?
Authority
Who are the authors of the resource?
Who published the information? Which organization is responsible for it?
To find out if a reputable institution is behind the site you can check the about section of the site or go to the home page.
You can also check the URL of the site. Look at the domain name (the domain is the first part of the URL, up to the first /).
Domains ending with .gov or .edu are USA government and university sites. You can look up the owner of domain names ending with .org, .net and .com at
http://www.networksolutions.com/whois/index.jsp
Currency
When was the information on the page originally written? When was it last revised? Are there any broken links on the page? Is there any information that is clearly outdated?
Don't trust today's date: on many sites this is generated by a script so the page seems current but isn't.