[Photo by Li Feng/China Daily]

Song Xuejun gets his kicks out of clicks, the sound emanating from any one of his two dozen or so wristwatches as he winds them. It is not just the sound that enthralls him as he goes through his regular ritual as a kind of master of time. Just looking at the watches' elegant inner workings and moving gears sends his mind into an enthusiastic spin.

"People tend to be hooked on their mobiles," says Song, 48, a company executive in Beijing. "But I like to communicate with watches; they're like friends. I don't buy them to show off; I buy them because I love them."

Song has become somewhat of an amateur horologist, regularly meeting like-minded individuals to compare notes, and, with his wife's backing, he puts money aside to buy his watches. He can afford this luxury because he belongs to an exclusive group that is perhaps the most talked about in China. Every habit of their lives seems to have been weighed, dissected and analyzed by researchers far and wide, and talk of their prospects preoccupies the global media.

This is the country's middle class, and sometimes it seems that on these people the future not only of China but the world economy hangs.

Unlike in many Western countries, the middle class in China is expanding, reflecting the way the country's economy and society more broadly are evolving. But who exactly are these people, and what does the way their lives are unfolding, with the myriad changes that will inevitably follow, hold for our future?

In October the Global Wealth Report by the Credit Suisse Research Institute in Switzerland said China had the largest middle class, 109 million people, compared with the United States' 92 million. (As a proportion of the population, the middle class of the US, accounting for about 30 percent, is of course far greater than that of China, about 8 percent.)