People tend to categorize or organize things to keep them simple and manageable. How we physically manage things is the same way our brain organizes or categorizes people in different buckets, often unconsciously, to ease the work. The categorization is based on previous experiences, likes or dislikes, prejudices, influences, and suggestions. This is what we call “unconscious bias.”
Biases can be classified broadly as Confirmation, Affinity, Attribution, Conformity, or Halo Effect. But I think it is beyond this because every brain has a distinct way of processing things. The unconscious is also called implicit or hidden because it’s outside of one’s conscious awareness and control. Most research studies suggest that people can act based on prejudice and stereotypes without intending to do so. It is essential to make a conscious effort to overcome our unconscious bias because, although we are unaware of the bias, it may affect our decision-making process.