Prejudice can be an affective feeling towards a person based on their perceived group membership. An unfair feeling of dislike for a person or group because of race, sex, religion, etc. When prejudice is put into action, this is discrimination. It would be unreasonable to say that anyone is completely free of internalised prejudices against others. It is our duty to recognise the prejudices we hold, and to question them. It is only when we begin to question our prejudices that we can begin to dismantle them effectively.
See: Bias and Discrimination.