Oppression is the unjust use of power.
Anti-oppression
Includes the strategies, theories, actions, and practices that actively challenge systems of oppression. Anti-oppression recognizes the oppression that exists in our society and attempts to mitigate its effects. Oppression operates at multiple levels, individual, institutional, and cultural, so anti-oppression must work at these levels as well.
What about diversity and inclusion?
Anti-oppression is different from diversity and inclusion. Diversity and inclusion work focuses on the acknowledgment, value, and celebration of differences, whereas anti-oppression work challenges the systemic biases that devalue and marginalize differences. These practices go hand in hand but they are not interchangeable.