Exchange-traded funds offer a convenient way to invest in sectors or niches that interest you. If you expect technology-heavy companies to thrive over time as our growing population embraces new and improved technologies, the iShares S&P North American Technology ETF (NYSE: IGM) 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 lots of them simultaneously.

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

This ETF has performed rather well, handily beating the world market over the past three, five, and 10 years. 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 9%, this fund isn't frantically and frequently rejiggering its holdings, as many funds do.

What's in it?
More than a handful of tech companies had strong performances over the past year. Qualcomm (Nasdaq: QCOM), for example, surged 31%, supplying many millions of iDevices and Android devices with its LTE chip technology. The company experienced a big hiccup earlier in the year, though, when supply shortages at Taiwan Semiconductor slowed its production. Qualcomm has been broadening its line of S4 Snapdragon processors for smartphones, but some worry that it may not be able to keep up with demand. To boost its capacity, the company has deals in place with Taiwan Semiconductor and others. Meanwhile, supply issues for the iPhone 5 may slow Qualcomm down at least a bit in the near term.

Data storage giant EMC (NYSE: EMC) is pleasing investors by expanding into flash storage technology, which is a high-growth business. It's expanding in emerging markets, too, in part by partnering with Lenovo to serve China. Management recently noted, "We believe we have the right strategy in place to leverage the three major waves of change in IT: cloud, Big Data and trust." Bulls also like its majority ownership of cloud computing specialist VMware and its new partnership with Cisco to offer a broad range of cloud services. Some wonder whether the cash-rich company might start paying a dividend soon, too.

Other companies didn't do quite as well last year, but could see their fortunes change in the coming years. Glass and fiber-optics giant Corning (NYSE: GLW) gained 9% over the past year. It has suffered from weakness in the LCD panel market, but demand is likely to perk up eventually, which will boost Corning's business. Meanwhile, Corning's Gorilla Glass is installed in millions of smartphones and tablets and the company has a promising new product, as well: Willow Glass, which is thin and flexible. It's expanding in the life sciences arena, as well, and has promising partnerships in place with Samsung and Dow Chemical.

Broadcom (Nasdaq: BRCM), up 5%, is making some smart acquisitions that can boost its presence in mobile computing. Like Qualcomm and Corning, its products are also found in many iDevices, which bodes well for its future performance. It's inside the Kindle and other devices, as well. Meanwhile, Broadcom has been making deals to get into inexpensive Chinese smartphones, too. Some see the stock as a bargain right now.

The big picture
Demand for technology 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.

If you'd like to learn more about Corning, check out our premium report on it, which will help you decide whether the stock belongs in your portfolio. Click here and get your copy today.