On Praja, a group is a collection of users who are passionate about a particular cause.
On Praja, there are two kinds of groups. One is for cities which can be joined by people who care about a particular city. These groups are visible when a user registers on Praja. Alternatively, users can also join a group at a later date.
The other kindof group is based on an issue or a cause. These groups can also be the online avatars of existing offline groups like citizen associations, NGOs etc. Each group is managed by its own admin who choses whether the group is open to everyone or an approval is needed to join. These groups do not appear on the registration page of praja. You can find out which groups are under praja by going to the groups directory here. If you want to join a particular group, just click on 'Join' the group and your request will be sent to the group admin.