Public websites are those that can be accessed through a search engine like Google. Like any information source, they represent their creator's point of view. Each site should be evaluated before using the information. This is a list of criteria provided by the University of Guelph Library:

Issues to consider:

• Determine the type of page/site you are reviewing. Is it a scholarly document, a personal web page, an advertisement, entertainment etc.?
• What are the goals/aims of the author in creating the page/site?
• Is the information likely to be biased in any way? 

• Does the author of the page/site have credibility? What evidence do they give of competence in the area they're discussing? Do they work for a reputable organization?
• How do the data and conclusions presented compare with other sources you've consulted?
• Are references (i.e. citations) given to substantiate the conclusions drawn? 
• Has the page/site been reviewed by the other knowledgable individuals to ensure standards of quality?
• Has the page/site been reviewed by one of the Internet reviewing services (e.g. Magellan)?

Currency

• When was the page/site first created? When was it last updated? Does the page/site appear to be updated regularly?
• Are the data and conclusions presented likely to be out-of-date or recent enough to still be valid? Documents in a rapidly advancing scientific area could be out-of-date or simply wrong within a year of creation.
• Check to see if all the links on the page are still active. Numerous inactive links suggest the page/site is not well maintained.

Reliability

• If you are going to refer to the document (or site)  in a prominent way in your work, can you be sure it will remain available for some time? A government web site is much more likely to be maintained for some years than that for a small company.
• Are there mirror sites? In other words, is the page/site duplicated at several locations on the internet for ease-of-access?

The internet can be searched like a library catalogue or journal index by using Boolean logic. Different search engines employ different protocols and it is a good idea to look at the engines help section before you start. As suggested before the Advanced Search function can be helpful in tailoring your query.