Purpose is important because books, articles, and Web pages exist to educate, entertain, or sell a product or point of view.
Some sources may be frivolous or commercial in nature, providing inadequate, false, or biased information. Other sources are more ambiguous concerning their partiality.
Varied points of view can be valid, as long as they are based upon good reasoning and careful use of evidence.
Why did the author or publisher make this information available?
Is there an obvious bias or prejudice?
Are alternative points of view presented?
Does the author omit important facts or data that might disprove a claim?
Does the author use strong or emotional language?
Look at the preface of author's notes for information about the book's purpose. For web sites look at About Us/Mission links, content, and advertising.
Determine the purpose of the web site: