* .gov means that the site is operated by the government. These sources tend to be credible.
* .edu means that the site is operated by an educational institution. These sources also tend to be credible.
* .org means that the site is operated by a non-profit institution. These sources tend to have an obvious bias but are also credible.
* .com means that the site is "commercial." Be cautious about these. Some, like newspapers and magazines, are highly credible. Others are just unsupported and inaccurate.Seek out professional-looking sites that deliver content that is well-reasoned, factual, up-to-date, and grammatically-correct.
Some places to start:
The New York Times
The Washington Post