Exchange-traded funds offer a convenient way to invest in sectors or niches that interest you. If you expect the networking industry to thrive as it keeps growing and taking on more work, the iShares S&P North American Tech-Multimedia Networking ETF (NYSE: IGN) could save you a lot of trouble. Instead of trying to figure out which companies will perform best, you can use this ETF to invest in several dozen of them simultaneously.

The basics
ETFs often sport lower expense ratios than their mutual fund cousins. The networking ETF's expense ratio -- its annual fee -- is a relatively low 0.48%.

This ETF has not performed spectacularly over the past 10 years compared to the S&P 500, but its future matters more. If you're bearish on networking's prospects, steer clear. But if you're bullish, consider this ETF; the market's recent deep swoon leaves most of its components priced more attractively than before. 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 25%, 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. InterDigital Communications (Nasdaq: IDCC) and Qualcomm (Nasdaq: QCOM), up about 138% and 21%, respectively, over the past year, are both patent giants, able to collect vast sums in fees from other companies using their technology. Part of InterDigital's rise owes to speculation that it might be acquired specifically because of its patents. Qualcomm, meanwhile, benefits investors by having chips using its technology in all kinds of mobile devices.

Other companies didn't add as much to the ETF's returns last year, but they could have an effect in the years to come. JDS Uniphase (Nasdaq: JDSU) fell 14% over the past year despite performing fairly well. The company bought Agilent Technologies' (NYSE: A) network solutions test business, which many expect to merge well with JDS Uniphase's own testing and measurement division. Sonus Networks (Nasdaq: SONS) may be down about 23% over the past year, but it's a strong player in the voice-over-IP technologies business. It's hiring more workers and expecting profit margins to grow in the near future.

The big picture
Demand for networking capacity and performance won't go anytime soon. A well-chosen ETF can grant you instant diversification across the industry -- and make investing in and profiting from the sector 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 ."