Why is ETF low risk?

Why is it that ETFs are often considered to pose low risk to investors? Could you please elaborate on the factors that contribute to their relatively safer nature compared to other investment vehicles? I'm particularly interested in understanding how ETFs achieve diversification, as well as the role played by their underlying assets and management strategies in minimizing risk exposure. Additionally, I would appreciate it if you could discuss any potential risks or limitations associated with ETFs, even though they are generally considered low-risk investments.