ETFs combine several attractive features in one product: broad, instant diversification across the securities in the underlying index or basket; typically lower expense ratios than actively managed funds, since most ETFs follow a passive, rules-based strategy; and the flexibility to buy or sell at live market prices any time during trading hours, rather than waiting for a single end-of-day NAV. Because holdings and the tracked index are usually published and well known, ETFs also tend to be transparent about exactly what you own at any point. For cost-conscious, long-term investors who want simple, diversified market exposure without picking individual stocks, ETFs can be an efficient building block for a portfolio.

An ETF's price can still fall along with its underlying index, sector or commodity, so it carries the same fundamental market risk as the assets it tracks. Actual returns can differ from the index due to tracking difference, arising from fund expenses, cash holdings and the fund's ability to replicate the index precisely. Liquidity varies by ETF: some have healthy trading volumes and tight buy-sell spreads, while thinly traded ETFs can have wider spreads that add a hidden cost when transacting. You'll also need an active demat and trading account to buy and sell ETFs, and unlike a mutual fund, every transaction happens on the exchange rather than directly with the fund house.