What is "echo chamber" in the context of social media, and why is it a concern?

An echo chamber on social media occurs when people are exposed primarily to opinions and information that reinforce their existing beliefs, often because of algorithms that suggest content similar to what they already engage with. This creates a feedback loop where differing viewpoints are rarely encountered, leading to polarized communities and a narrowing of perspectives. The concern with echo chambers is that they can entrench bias, reduce critical thinking, and contribute to societal divisions, as individuals become less likely to engage with or understand opposing views.