XIAMEN - College students from Taiwan and the mainland used to take down email addresses and MSN accounts on their notebooks when they parted from each other after attending cross-Straits activities.

Now, as many Taiwan?people?attended the ongoing fifth Straitss Forum in the coastal city, they befriended mainlanders by shaking their smart phones and finding the other's avatars on a popular app called WeChat.

For many people on the island, the mobile application, developed by mainland IT giant Tencent to feature voice messaging and photo sharing services, offers a new way of interaction with the mainland, with which they have closer ties thanks to improving cross-Straits relations.

Lin Ting-cheng, a college student living in the island's Tai Chung city, has more than 100 mainland friends on WeChat and QQ, an instant messaging service also operated by Tencent.

"I exchanged my account with many others when I traveled to the mainland, and now we chat a lot on the Internet and many of them ask me about the island's tourist destinations as they prepare to visit here," Lin said.

Taiwan and the Chinese mainland broke off communication in 1949, after the Kuomintang (KMT) lost a civil war with the Communist Party of China and fled to Taiwan.

Cross-Straits exchanges and travels were only made convenient after 2008, when a new generation of KMT leaders adopted mainland-friendly policies and the two sides opened direct mail, transport and trade links.

In recent years, many social networking services including Twitter-like Weibo and QQ, whose traditional user bases had been on the mainland, have gained popularity among the Internet-savvy population in Taiwan.

Hsu Pao-huan, manager of a Taiwan-based advertising company with many clients on the mainland, said though messaging app LINE remains more popular in Taiwan, WeChat is winning over users with its provision of convenient communication with mainlanders.

Chen Yun-sheng, who works with Cti TV in Taiwan, uses WeChat to gather his mainland friends before each weekend's mountaineering activity and later posts photographs on the app's twitter-like "Moments" sector.

"I started using WeChat after seeing a friend at a mainland TV station shaking his smart phone," Chen said. The app allows one to acquaint nearby users by shaking the smart phone.

Using its search function, a Xinhua reporter stationed in Taiwan found 150 WeChat users within 1,000 meters.

Industry observers estimated the number of the island's WeChat users at somewhere between 5 and 6 million.

At the popular migroblogging site weibo.com, many Taiwanese celebrities and public figures who have registered their accounts are followed by millions of mainland fans.

Chen Ching-chao, a Taiwanese lecturer at Xiamen University, has opened accounts in several social networking websites or apps popular on the mainland, such as Kaixin, Renren, Weibo and WeChat.

Chen said the booming popularity of mainland social networks among the Taiwanese was a reflection of grassroots exchanges between the two sides. Many Taiwanese youth began using the networks when they came to study and work on the mainland, he said.

On Sunday, the mainland rolled out a package of preferential policies on Taiwan, which analysts said focused on facilitating grassroots exchanges and improving the lives of ordinary Taiwanese people.

"Social networks have brought Taiwanese and mainlanders closer to each other, promoted their mutual understanding and created more opportunities for cooperation," Chen said.