A broad term that describes how widgets and Web apps (also known as mini-websites) can be shared and interacted with amongst existing online communities and social networking sites. Basically social networks and other websites (also known as platforms or containers) can let companies extend their website experience to existing communities on popular social networks using mini-applications.
There are several reasons why open social is so alluring for Web companies:
Web marketing is no longer limited to a corporate Web site.
There is efficiency in development, meaning there's standardization in the code use (APIs) so if you develop an application for OpenSocial, it should be easily re-used on all the social networks that are particiating.
You can harness existing communities and therefore the need to build an audience isn't as crucial.
The open standards help in the long term, meaning the standards and development languages are commonly known and not proprietary so it reduces the chance of vendor lock in.
Your existing applications become social, in other words, your standalone applications can now be shared with communities.
Open social systems are yet to be proven and there are many inherent challenges, such as open data risks, inconsistencies, and cultural differences. Nonetheless, Silicon Valley is jumping on the open social bandwagon as part of a later Web 2.0 development. Film at 11.