The ideas that make StackOverflow.com so great are summarized at:
- Voting: There needs to be a way to rank answers to a question up or down so you can see the best answer the first.
- Tags: Hierarchical categorizing fails where tagging works wonderfully.
- Editing: You need to be able to edit both questions and answers so they do not become obsolete.
- Badges: Users should gain status by completing actions on the site that gain knowledge on the site features and make people use them.
- Karma: Users should gain status by asking good questions and replying with good answers.
- Pre-search: Asking a question needs a search first. It really prevents duplicates.
- Google is UI: Google should be able to index the whole site for users to access questions.
- Performance: A performant site is used.
- Critical Mass: Users will only use sites that trust on. And stackoverflow.com was developed by two very influential IT bloggers.