It's easy to fall into certain habits when you think about investments and your portfolio. Sometimes these habits make a certain amount of sense -- investors with a lower risk tolerance shouldn't generally be buying microcaps, while aggressive growth investors shouldn't be buying AAA-rated corporate bonds. But sometimes these habits can do as much harm as good.

Take global investing, for example. Do you think of it as investing "abroad?" Or perhaps as investing in "foreign" stocks? That "foreign" part sticks in my craw. How foreign are Toyota or Honda, when you look around a shopping-mall parking lot? How foreign are Samsung, Sony, or Matsushita, when we have their electronics in our houses? How foreign are Roche and GlaxoSmithKline (NYSE:GSK) when many Americans depend on their medicines for their very lives?

I believe we should do away with the concept of "foreign investment." Sure, I know it's a handy way to refer to buying stock in a company that "ain't from 'round here." But I think too many people get hung up on the supposed dangers and differences in global investing, missing its opportunities in the process.

What is a "foreign" stock?
Really, what qualifies as a "foreign" stock these days? If Infosys (NASDAQ:INFY) is foreign because it's based out of Bangalore, what about the nearly two-thirds of its revenue that comes from the United States? And is Central European Distribution really American when it's based out of Philadelphia, but gets virtually all of its revenue from Poland?

Think, for a moment, about what McDonald's (NYSE:MCD) or Coca-Cola (NYSE:KO) would be without their huge foreign markets. I haven't yet traveled to a country that doesn't have the golden arches somewhere in its borders, and "Coca-Cola" is supposedly the second-most recognized word in the world (after "OK").

What's more, I'm struck by just how many companies around the world offer their financial information in English, even if the company's stock isn't listed on an exchange in an English-speaking country. Moreover, many companies are increasingly adopting attitudes toward bookkeeping, auditing, and shareholder information that are quite similar to the standards and practices we've enjoyed for quite some time.

No place to hide
The more you follow the news, the more you realize that separating companies into "domestic" and "foreign" folders rarely reflects the reality of the world anymore. North Korea's belligerence is really only a physical threat to South Korea and Japan, but our bond and gold markets get jittery when the Dear Leader ratchets up the rhetoric. And bond and gold traders' nervousness often spills over into equities as well.

It probably wouldn't take you long to think of numerous other examples. Oil is certainly a global market, where events in far-off places have very real consequences at the local ExxonMobil (NYSE:XOM) station. And what of the recent intellectual property and antitrust tangles between European officials and American tech companies like Microsoft (NASDAQ:MSFT) and Apple (NASDAQ:AAPL)?

Any way you slice it, the market truly is global. American firms rely on cheap manufacturing in China or cheap services in India, while Chinese and Indian companies rely upon Americans' desire to save a buck or two on a TV or pair of slacks. But if you're investing only in American companies, I might argue that you're subjecting yourself to asymmetrical risk -- concentrating your risks a bit too much in one place, and perhaps missing out on greater growth elsewhere.

Capital has a passport
Following the smart money is a tried-and-true philosophy at The Motley Fool, and the smart money has been going overseas for a while now. Recent examples would include Berkshire Hathaway buying an Israeli company and Goldman Sachs buying a British port operator, but numerous other examples all point to the same idea -- capital can, and should, travel across borders in search of the best deal its owner(s) can find.

True, the average American investor won't be launching a takeover of a Korean company, nor playing the Chinese version of penny stocks. But the growing interconnection of financial markets does mean that there are ample opportunities to invest outside of companies headquartered in the United States. Not only are there good mutual funds devoted to global (or country/region-specific) investing, but dozens and dozens of investable ADRs out there also allow Americans to buy shares of foreign stocks through their regular brokers.

Think globally, act locally
I can't honestly tell you that you can invest in Japanese companies as easily as you can in an American company. Heck, it's not always easy to invest in Canadian companies, and they're our next-door neighbors. But I can tell you it's worthwhile. Some of my top-performing holdings are foreign -- excuse me -- non-U.S. companies, and I don't expect that to change.

We at The Motley Fool really do believe in investing abroad. We recently published our inaugural international stock report, Around the World in 80 Minutes, and our new report, 10 Monster Stocks, also includes several top-notch picks that are highly dependent upon the global economy. (In fact, one isn't a U.S. company.)

The habit of thinking about "foreign stocks" as somehow completely separate from U.S.-based companies is out of date. If you cling to it too tightly, you may even undermine your own performance. After all, if you're investing in large-cap U.S. stocks, the odds are pretty good that you're already investing globally, even if you don't think of it that way.

Forget about investing in hot countries, and forget about allocating a fixed percentage of your investments to "foreign stocks." Instead, search the globe for the best companies you can find, and buy them when they're trading for less than they're worth. Do that, and you just might profit from the fallacy that foreign stocks are somehow different, unique, or separate from normal investing.

For more Foolish thoughts with a foreign flair:

To purchase a copy of Around the World in 80 minutes, click here. To buy 10 Monster Stocks, click here.

Fool contributor Stephen Simpson has no financial interest in any stocks mentioned (that means he's neither long nor short the shares). Glaxo is an Income Investor pick, while Microsoft is an Inside Value selection. The Fool has a disclosure policy.