The service is currently only open to specially invited testers. It has been developed as a social networking website where you can share your life experiences with friends and family, Reuters reports.
Mash is Yahoo's second attempt to launch its own social networking website - in 2005 it launched Yahoo 360 degrees. However, the new service is entirely separate from the previous site, Yahoo said.
"Ongoing product innovation is important to Yahoo and we continue to test various products and services to gain feedback from our users. Mash, an experimental profile service, is an example of this ongoing testing," a company spokesperson said.