Prejudice comes from the words 'to judge before'. It is forming an unfavourable opinion or feeling about a person or a group of people, without a full examination of the situation. In theory, it is possible for somebody to be prejudiced without anybody else knowing about it.
Discrimination is making a distinction against a person or thing based on the group, class or category they belong to, rather than basing any action on individual merit.
A simple distinction between prejudice and discrimination is that prejudice is to do with attitude, discrimination is to do with action.
Forms of discrimination include verbal slurs, failure to provide reasonable accommodation or access, media portrayal, preferential pay, hiring or admissions policies and hate crimes. Discrimination can be committed by individuals, groups or institutions.
Positive discrimination is where a particular group is given special privileges to compensate for a perceived disadvantage. For example, disabled people can often access parking spaces closest to a building's entrance.