Stack ExchangeThe system of questions and answers.
This is a whole group of sites with questions and answers with a multimillion audience.
People ask questions and give answers to these questions.
The system notices the activity and determines the rating of questions by it. So invisibly people themselves vote.
Users earn reputation and badges for participating in the project. The higher the reputation, the more rights up to the ability to edit other people's materials. However, full moderator rights will not work.
QuoraA place to gain and share knowledge.
It's a platform to ask questions and connect with people who contribute unique insights and quality answers.
This empowers people to learn from each other and to better understand the world.
address: USA, New York, 110 William Street, 28th Floor, NY 10038
SuperuserSuperuser is a concept understood by smartphone users.
This is a question and answer service for computer enthusiasts and experienced users.
It's easy to join. It makes sense to join here, because one of the most popular.