There are many potential aspects of responsibility in recommendation, including (but not limited to):

• Bias and discrimination in recommendations

• Imbalance in meeting the needs of different groups of users

• Balancing needs of users versus recommendation system owners

• Ethics of explore/exploit strategies or A/B testing

• ‘Filter bubble’ or ‘balkanization’ effects

• Clickbait

• Transparent and accurate explanations for recommendations

• User data privacy