What is a bias? How can biases affect the scientific process?

Bias is your opinion or belief on something this effects the scientific process by letting what you think get in the way of what the actual results are making the whole process come to an error

Such bias is not necessarily malicious but is inescapable. Bias produces not merely systematic errors or useless results. Bias often guides the very research questions, the construction of procedures thought useful in investigating those questions, and regularly produces useful results.