How To Choose An Exchange Traded Fund."
Exchange-Traded Funds are a lot like index mutual funds, but you buy and sell them like stocks. They also often offer lower fund management fees than their index fund counterparts.
They are ideally used when you're making a lump-sum purchase because you pay the stock brokerage fee of as little as $4.95 no matter how many shares you purchase; your purchase transaction cost per share drops the more you buy.
They're great for buying into markets in different countries, regions, and industries. While they should not be the bulk of your portfolio, they can round out your portfolio by exposing you to other markets that offer different risks and potentially higher returns.