Confirmation Bias is a natural human impulse to seek out, interpret, and absorb only the material and information that aligns with one's pre-existing beliefs, values, or worldview. This is not bad in and of itself. After all, if one prefers puppies to kittens and only shares puppy photos with family and friends on social media rather forwarding images of felines, the bias is innocuous. And preferences are a healthy part of human life. It is what helps to make use individuals.
The difficulties however, are twofold.
The first is that if we aren't exposed to other points of view, we may not learn and grow. One needn't adopt an opposing veiwpoint, but it is still valuable to understand the reasons why someone else takes the position they do. That leads to healthy behaviors such as empathy, informed understanding of current events, and yes, even the knowledge base to negotiate compromises that contribute to the greater good when that is appropriate.
The second problem occurs when misinformation aligns with one's beliefs. Sometimes, without thinking too hard about it, one simply takes that misinformation at face value as genuine and using it to justify (confirm) beliefs, actions, or decisions. If the misinformation sounds good, we may even be inclined to share it with others.
Conformation bias also plays out:
Individuals may not be aware that they are exhibiting conformation bias in relation to media. These are some characteristics identified by Daniel Fishel and Kendra Cherry of Verywell Mind:
Disinformation, when it appeals to confirmation bias, is intentionally used by foreign adversaries who may plant stories in an effort to divide Americans, erode public faith, and ultimately weaken the United States (American Security Project). It is a very effective tool.
Related to confirmation bias is the notion of filter bubbles. The ability to personalize the information one receives, either by intentionally selecting media and news sources or by having them selected on an individual's behalf by algorithms that track clicks and cookies and send you more of the same, means that one can effectively live in an isolated bubble or echo chamber where one only is exposed to a very narrow range of cultural, ideological, or even topical slate of information. Now filter bubbles aren't all bad. A filter can help ensure that a dog lover doesn't have to wade through uninteresting videos of kittens. At the same time, however, it may mean that one never is exposed to a perfectly fascinating videos about ferrets. One is like a proverbial ostrich who only sees the grains in its little bubble of sand. For more on Filter Bubbles view the Ted Talk video, "Beware online 'filter bubbles'" by Eli Pariser (March, 2011).