Vanguard's low-cost ETF series offers a convenient way for long-term diversified investing. The Vanguard Total Market Stock ETF (VTI) covers over 3,500 U.S. stocks across a wide range of market capitalizations. If investors focus on the stability of large-cap stocks, the Vanguard S&P 500 ETF (VOO) tracks that benchmark index. Additionally, the Vanguard International Stock ETF (VXUS) holds over 8,500 stocks from developed and emerging markets, enabling international diversification. These funds all emphasize low expense ratios and broad market coverage, aligning with a passive buy-and-hold investment strategy.