Bias: its most common forms in HR and how to avoid it

HR professionals will certainly be familiar with the term "bias", which refers to prejudice or misconception. These are often unconscious prejudices about people we meet or deal with, and they can affect sound, rational judgement. HR managers should try to avoid these biases at all costs, not only to prevent discrimination but also because they could harm both themselves and the company by making poor decisions based on faulty assumptions. What are the most common forms such biases take in HR? And how to avoid them?