Open web sources can be searched, typically using search engines such as Google, and are available on the internet without requiring authentication (such as user name & password, or a payment being made).
Because anyone can publish anything online, it is very important to take extra time evaluating these resources.
Fact Checking Websites
Do not forget to check the "About" sections of these websites...
American FactFinder contains data from surveys and censuses conducted by Census Bureau (nearly one hundred of them every year.). You can find economic, demographic or housing information about your city, county, state - or the entire United States.