Exchange-traded funds offer a convenient way to invest in sectors or niches that interest you. If you expect the industrial sector to thrive as the global economy eventually recovers, the Vanguard Industrials ETF (NYSE: VIS) could save you a lot of trouble. (Even if you think the recovery is not around the corner, you might want to keep this fund on your radar.) Instead of trying to figure out which companies will perform best, you can use this ETF to invest in lots of them simultaneously.

The basics
ETFs often sport lower expense ratios than their mutual fund cousins. The industrial ETF's expense ratio -- its annual fee -- is a low 0.24%.

This ETF has a reasonable performance record, slightly outperforming the S&P 500 over the past five years and losing to it over the past three. As with most investments, of course, we can't expect outstanding performances in every quarter or year. Investors with conviction need to wait for their holdings to deliver.

With a low turnover rate of 10%, this fund isn't frantically and frequently rejiggering its holdings, as many funds do.

What's in it?
Several of this ETF's components made strong contributions to its performance over the past year. Railroad company CSX (NYSE: CSX) gained 29% over the past year, building volume and also profiting from price increases. Better still, the company expects strong double-digit growth through 2015. The growth is partly driven by a shift in freight transport from trucks to rails, exemplified by a recent arrangement between FedEx (NYSE: FDX) and Norfolk Southern (NYSE: NSC).

Caterpillar (NYSE: CAT), meanwhile, gained 18%. Bulls are excited about its purchase of mining equipment maker Bucyrus and how that can draw mining dollars from China, Brazil, and Australia.

Other companies didn't help the ETF's returns last year, but could have an effect in the years to come. Waste Management (NYSE: WM) shed 9% of its value, but has been investing heavily in its recycling business and has a cost-reduction program underway. (Interested investors should note that it sports a hefty dividend yield, too, recently topping 4.5%.) Boeing (NYSE: BA) also lost about 9% over the past year, partly due to repeated delays of its much-anticipated 787 Dreamliner -- which my colleague Evan Niu has called "the unicorn of aviation." (It appears to be finally debuting.)

The big picture
Demand for industrial companies isn't going away anytime soon. A well-chosen ETF can grant you instant diversification across any industry or group of companies -- and make investing in and profiting from it that much easier.

ETFs can help you find the way to better investing results. To find some great ETF investing ideas, take a look at The Motley Fool's special free report, " 3 ETFs Set to Soar During the Recovery ."