Is it peer-reviewed? The peer-review process used by many scholarly journals is designed to guarantee a certain amount of accuracy and quality in the publication of scholarly information.
Is it unverified or fake news? If one statement on a web page is false, the rest is also suspect. Urban myths are often passed around as facts, and facts "everybody knows" may not be true. Look for the original source when possible. Be cautious if you can't find the author's name or credentials. An exception is a magazine or newspaper article written by an unnamed staff reporter. When there is no author given, the authority of the source is based on the reputation of the publisher or producer of the information.
Be skeptical of a web site that touts the benefits of an alternative medical treatment when it includes a link to buy the product, for example. For a political issue, make sure you get information from organizations or individuals on more than one side of the issue.
Statistics: Don't expect up-to-the-minute statistics for everything! It takes time to compile and publish them. Keep in mind that sometimes the information is published long after it is collected.
Medical and Health: It is especially important that medical and health information be up to date. You could use an older source for history and background information, but make sure you check more recent sources for new developments. Generally, older than 5 years is considered out of date for clinical use.
Look closely at the language used in the information source. Examine the types of adjectives and verbs used; is there evidence of superlatives/absolutes (“always” and “never”), emotional/sweeping generalizations, and exaggeration? Example: "This is obviously the most important idea ever conceived!" or "All teenagers are distracted drivers since they are always texting."
This guide from Johns Hopkins University includes more detail on how to identify misinformation and how to track down authority and currency of a website.
