A wiki is a web platform that enables multiple users to collaboratively create, edit, and arrange content through a browser.

Simplicity and openness are central to wikis: anyone can often add or change pages without technical knowledge, and edits are usually logged for review or rollback.

Common features
- **Collaborative editing:** Several contributors can edit pages, sometimes at the same time.
- **Edit history:** Each change is logged with a time and the editor’s name or IP.
- **Interlinking:** Links between pages are simple to create, helping build connected content.
- **Lightweight markup:** Formatting is usually handled by lightweight markup languages (e.g., WikiText or Markdown).
- **Permission settings:** Wikis may allow public editing or restrict changes to registered or authorized users.
- **Discussion pages:** Separate talk pages allow contributors to discuss edits and structure.

Typical uses
- Community knowledge bases such as Wikipedia
- Internal documentation and company knowledge bases
- Cooperative writing and shared notes
- Educational and classroom projects

Benefits
- **Fast collaboration:** Contributors can rapidly create and improve content.
- **Openness:** Transparency through revision histories and discussions.
- **Expandable:** Wikis expand easily as contributors add and organize content.

Drawbacks
- **Vandalism and false information:** Open editing may allow intentional or accidental inaccuracies.
- **Inconsistent quality:** Articles can differ greatly in depth, tone, and reliability.
- **Organizational issues:** Lack of structure or rules can lead to disorganization and conflicts.

Notable example
- **Wikipedia** — the best-known wiki, run by the Wikimedia Foundation and built by volunteer contributors worldwide.