Having a second child has greatly changed the lives of Xu Jihang and his family. [Photo provided to China Daily]

If you are talking about a middle class, you need to be sure about exactly which one you are talking about. Definitions of the term differ not only from expert to expert but from country to country.

Zhang Haidong, a professor in the School of Sociology and Political Science at Shanghai University, says that in the West the term middle class usually refers to people such as executives, professionals, salespeople and office workers, while in China many of the emerging middle class are the self-employed, such as traders and owners of businesses.

Ultimately, too, such people are from all kinds of backgrounds, and the paths that have taken them to the middle class and the lives they lead are many and varied. Here are the stories of three members of China's middle class.

The charity worker

For Su Zhongxi, 33, helping others not only keeps him fed and clothed but gives him immense career satisfaction.

After working for domestic and international charitable groups for seven years he decided in 2013 to set up a consultancy to help such organizations do promotion and raise funds and help them and business better communicate with one another.

"For me, public service is about raising people's awareness of important issues and ensuring people know how to help those in need," says Su, of Beijing.

Some passionate grassroots organizations need promotion for their public service programs, he says, and some companies want to fulfill their corporate social responsibilities and want to find a good project to support but do not know where to look.

Last year his company started to promote the First 1,000 Days project of the United Nations World Food Programme. It aims to ensure all children receive the nutrition they need during their first 1,000 days－between a mother's pregnancy and her child's second birthday.

"It means a lot to infants. Good nutrition during the critical period brings lasting benefits to them－they are healthier and perform better in school."

The five-year project in China calls for the public to focus on the issue and help mothers in impoverished areas. Its image ambassador is Li Na, the retired two-time tennis Grand Slam champion.

Su is also keenly interested in animal rights and welfare. He has been a vegetarian for 10 years. He explains that it is because he believes in protecting animals and he wants to be healthy.

"It influences others as well. My parents and several friends are not as into meat as they used to be."

When he was a teenager he noticed that horse-drawn carts were widely used to transport bricks and was shocked by the sight of owners whipping horses to get them to move.

Once he saw a horse lying on the ground after a crash, badly injured. The groom was bargaining compensation with the bus driver, rather than trying to save his companion, he says.

"These creatures really need to be treated humanely."

After graduating from university he became a volunteer with an animal protection association, and later, keen on promoting awareness of the rights of animals, he quit his job with an international company and became a full-time NGO worker. At first, he only saved stray animals, but then started to do animal welfare work because he wanted to help the group rather than individuals.

Such work has helped him understand how importance empathy is, he says, both for animals and human beings.

"Some friends sometimes come to me wanting help with relationship issues. My secret is to tell them to put themselves in other people's shoes."

Su says that with the rapid development of the economy and Chinese society, more and more Chinese are aware of the importance of protecting animals and the environment, especially younger people.