It is important to evaluate the information you access and use especially if it is from the web. Because anyone can create a web page it is important to to distinguish reliable information from bad information or misinformation on the web.
The author should be held to the same degree of credentials and authority that one would expect from something published in a reputable print resource (book, journal article, reputable newspaper, etc.).
Use the CRAP test to evaluate sources in print and on the web based on the following criteria: Currency, Reliability, Authority and Purpose.
Currency
How current is the source? Is it current enough for your paper? If it is a website, when was the site last updated? Is there any indication about the currency of the information? For some disciplines or topics, currency may not matter.
Reliability
Is the information in the source free from bias? Is it opinion or fact? Is it balanced and objective? Can you verify the information provided through other sources? Do you perceive a conflict of interest in terms of the content or presentation of the topic?
Authority
Who is the author of the book or the web site? Is the author a well-known scholar in the field? Is contact information provided for the author? Is the author affiliated with an educational institution or credible organization? If it is a web site, who is responsible for the domain? Pages originating from an educational institution (.edu) or the government (.gov) are reliable. Personal pages or pages originating from .net or .com are not necessarily bad but you should be more wary and spend time verifying the information.
Purpose
What is the purpose of the information? Does the page exist to provide information or to sell a point of view? What is the tone of the page? Is it ironic? Does it ridicule? Is the information comprehensive? Is it geared toward a particular audience?
Here is a short YouTube video on the CRAP Test.