According to the AllSides Red Blue Dictionary:
This word has largely come to be seen as something negative - reflecting the undue influence of any sort of prejudice over our judgment or decision making. Since this influence is understood to distort that judgment and decision making, the goal is often taken for granted as to become free of bias" or "unbiased" in our assessments of the world around us.
This word "unbiased" is thus often synonymous with "objective" and "neutral." Out of this view, accusations of political bias are often made as an attack on various news networks or others presuming some kind of objectivity or neutrality - e.g., scientists and scholars.
From another perspective, some sort of standpoint or bias is an inherent and innate feature of the human mind - and something that literally cannot be "escaped" or "shelved." If that is true, some would argue this "bias against bias" may cause problems by pressing people to not acknowledge their biases and pretend they do not exist. As an alternative way to seek fairness and objectivity, diverse voices may be invited to acknowledge their biases in an open, transparent way that allows a discussion to be aware of what informs it.
It is important to be able to identify bias, especially when writing for a key audience in mind. One useful tool that can help is the Media Bias Chart, which provides a ranking system of bias level in hundreds (if not thousands) of media sources. This might be able to help you in determining a neutral source from one that may be trying to persuade. Click around and see if any of the chart positions surprise you!
Whether we like to admit it or not, everyone has some sort of bias simply from being exposed to the beliefs and ideals of the environment in which they were raised. Taken a step further, what is now known as filter bubbles or echo chambers can limit the information that can even reach you in the virtual world. Below is a Ted Talk by Eli Pariser, who was one of the first people to recognize and name this phenomenon:
While you're researching, practice SIFT to check the validity of a source: