Government (.gov or .mil) - Government websites end in .gov are among the most reliable sources on the web. BUT beware of political sites, their intent is usually used to sway public opinion.
University (.edu) - University web sites end in .edu, are usually reliable.
Company Websites (.com) - Company web sites generally end in .com. These sites are great for information about a particular company. However be aware that company websites are used to promote, so be sure the information is non-biased.
Special Interest (.org) - While many professional organizations end in .org, there are also many .orgs that are biased and promote a specific agenda.
When you search for information, you're going to find lots of it...but is it good information? You will have to determine that for yourself, and the CRAAP Test can help. The CRAAP Test is a list of questions to help you evaluate the information you find. Different criteria will be more or less important depending on your situation or need.
Currency: The timeliness of the information.
Relevance: The importance of the information for your needs.
Authority: The source of the information.
Accuracy: The reliability, truthfulness and correctness of the content.
Purpose: The reason the information exists.