Evaluate your source's...
Is your source
Recent? Reliable? Relevant?
Is this source up-to-date? Is it about my topic, and does it go into enough depth? Does it come from an authoritative source? Is the information accurate (and are there citations given to back it up)? And why was this information written in the first place?
While these domains tend to be a bit more reliable than regular .com/net/whatever domains, there are still pitfalls you can encounter. You should always be on the lookout when selecting your sources, and keep in mind evaluation criteria like the CRAAP test to guide you through taking a closer look.
In order of reliability:
Higher Education (mostly). Pretty restricted. Mostly university websites, but this limitation is relatively recent, and there are some .edu sites out there that were grandfathered in.
Caution! Watch out for student work that's publicly posted. Undergrad projects are not a recommended source.
Organizations. Limited to organizations... but organizations cover a wide spectrum of possibility. Many have a specific point of view or advocacy cause, which is not quite the same as having a bias, though they may have a bias, too.
Caution! It doesn't take much for someone to create an organization and register this domain. You really have to scrutinize who the org is.
You can steer your results towards better sources by telling Google to only give you .edu or .org or .gov sites. Example below: