It is important to be able to tell the difference between reliable sources. There are a lot of websites on the internet, and anyone can make a website. Many websites are based on people's opinions, have outdated data, or questionable information. It is important to know how to evaluate a website to determine if it is a legitimate resource.
Cartoon taken from: http://techieteacher5280.blogspot.com/2011/12/evaluating-websites.html