look at things like:

-Sources the author relies on.

-The author’s use of language. For instance, does the author use words with negative connotations about one side but words with positive associations about the other side?

– What examples does the author give? Are they typical or are they naturally going to support one conclusion over the other whereas a more neutral example could have resulted in another conclusion or a mixed view of the topic?

– what groups is the author associated with? For example, an author paid by a group that supports one side of the argument’s likely to be biased for that side.

Why is it important?

a biased author is likely to give an unfair, one sided view of the subject. Bias means that you have to do your own search to see if the biased author has given the whole story. But still, just because an author is biased doesn’t mean that what the author’s saying isn’t correct.