Zhou Huijuan gives a lecture on Nushu, a female-only language, at a night school?in a village in?Jiangyong, Hunan province. [Photo provided to chinadaily.com.cn]

A woman in her 70s in Hunan province has taken to the internet to keep alive a centuries-old writing system used only by women.

Nushu, probably the world's only female-specific language, was created in the late Ming (1368-1644) or early Qing (1644-1911) dynasties. It was used by women in Jiangyong, Hunan province, to share ideas and emotions through a set of codes unknown to men.

The language was added to China's list of intangible cultural heritage in 2006.

Zhou Huijuan, 75, runs a Nushu free night school in a village in Jiangyong. To make her classes available nationwide, she started to give lectures online, Hunan Daily reported.

The writing system was traditionally passed down through generations orally, but by the 1990s, many of the women who could read and write Nushu had passed away.

Zhou started to learn Nushu when she was 6 years old from her aunt and older sister, and now she is a master.

In 2007, she started a Nushu school for girls to preserve the tradition, and to her surprise more than 50 girls registered for the class. However, the school encountered financial difficulties and was shut down a year later.

Last year, Zhou reopened the school with the support of her husband and taught more than 200 students in one year.

"Now, many students watch the online classes and send me their homework using express delivery services. Some 20 students have graduated with excellent marks," Zhou told Hunan Daily.

Li Lei contributed to this story.