Searching Google: Domain searching
Search: politics art site:edu > will return results from educational websites - i.e. www.calarts.edu; www.ucla.edu; www.csun.edu; etc.
You can indicate any domain > site:gov (government); site:org (non-profit), etc.
Search: politics art filetype:pdf > will return only PDFs in your results
You can indicate any type of file
More Google search operators available here
Authority & accuracy
Who created the site? What are their credentials?
Purpose & content
What is the domain? Are they trying to sell you something? Inform you? Sway your opionion?
How current is the information? Is there a date on the site for when it was last updated?
Design & organization
If it looks like the site was designed by a 10 year old, then it probably was. Compare: http://www.terrorism.com/ and http://www.pewinternet.org/