Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

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Discussion group service provided by Google

Google Groups is a discussion group service from Google. Alongside the groups and discussions created by the users, it also includes Usenet newsgroups.

Groups can either be invite-only or open to the public, or, if the group is created within a Google Apps for Business domain, open to users of that domain.

The service started out as Deja News before the transition to Google Groups following a buyout in 2001.

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