Effective altruism is a philosophy that uses evidence and reason to determine the most impactful ways to improve the world. It aims to allow people to give charitably not just with compassion but also rational analysis. For example, it could cost $50,000 to train a guide dog to assist one blind person for around 8 years, whereas curing the underlying cause of blindness in the developing world through treatment may cost just $20 and help someone for their lifetime. Effective altruism suggests maximizing benefits by considering which causes have significantly larger impacts.