Bias

Bias is difficult to define objectively, but includes at least:
 * cognitive bias common to all human beings and built into our perception, memory, and instincts
 * cultural bias derived from our social surroundings, family and customs, well understood in pluralistic societies, e.g. Muqadimmah, an early Muslim view
 * notational bias of our languages, as explored in cognitive linguistics and cognitive science of mathematics
 * infrastructure bias related to our tools at hand, e.g. "if you have a hammer every screw look like a nail"
 * confirmation bias, rampant even in the sciences, where the original assumptions prejudice conclusions to avoid contradicting those original assumptions
 * self-interest of an economic, ethnic or religious group nature
 * groupthink, the tendency of groups in live meetings to agree with authority, if only to get out of the meeting faster.

Media bias consists of all of these and more related to journalism practices accepted professionally in different countries or traditions, and pressures applied by advertiser, government, regulator, owner and reader/viewer, each of which perceives themselves as "unbiased" - laughably. See also systemic bias and point of view.