For many people, studying Chinese is nothing more than a mild flirtation, but for others it is the Holy Grail, their very reason for being in China.

I'd like to say a foreigner's interest in learning Chinese stems from a deep-seated desire to understand China's ancient and mysterious culture but, frankly, the motivation is often more pragmatic. The temptation to cash in on this booming economy is irresistible. Learn the lingo and the world is your oyster.

Call it what you will, more foreigners are learning Chinese than ever before, many of us burying our heads in textbooks and homework for the first time in decades.

As growth industries go, it is a phenomenon. Only 20 years ago, less than 8,000 foreigners studied Chinese in this country. By the turn of the century it was up to 50,000. By 2004 it was 86,000, and the government estimated then that the number would be 120,000 by the time of the Olympics. Talk about an opening-up. This is a deluge.

If that isn't impressive enough, include the rest of the world in the picture. Even 10 years ago, it was estimated nearly 100 million people around the world were studying Chinese and about 100 countries were offering Chinese courses in various educational institutions. One result of this growing demand was a dire shortage of Chinese teachers and urgent requests to this country to send out more.

The burgeoning growth statistics are borne out by Zhao Changzheng, who has taught Mandarin at Peking University for seven years.

"When I came here we only had 300 foreign students learning Chinese," he says. "Now it's around 500-600 and we could have many more if we wanted.

"The university is keen to expand the department to 1,000 new foreign students each semester but we don't have enough room in the classes and dorms. Soon we will have a new building for foreign students and then the number learning Chinese will be as high as 2,000 each semester."

The geographical breakdown has also changed. "Ten years ago, it was just called the Chinese International College for Language Study and we mostly had Japanese and South Koreans," says Zhao. "In the last 4-5 years we've experienced such an surge of interest from the US that Americans are our biggest group, about 40 percent of all foreigners."

The benefit to the university has been more than merely financial. "Years ago, when we didn't have many applications to our department, we had no choice who we took," he continues.