Wikis are websites built for collaborative authoring, allowing numerous contributors to add, edit, and structure content online.

Wikis prioritize ease of use and openness: pages can be added or changed without technical expertise, and most track every edit so changes can be reviewed or undone.

Key features
- **Collaborative editing:** Multiple people can edit the same pages, occasionally concurrently.
- **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:** Simple markup languages (such as WikiText or Markdown) are used to format pages.
- **Permission settings:** Wikis may allow public editing or restrict changes to registered or authorized users.
- **Discussion pages:** Talk or discussion pages let contributors debate edits and organization.

Typical uses
- Community-driven knowledge bases (for example, Wikipedia)
- Project documentation and internal company knowledge repositories
- Group writing and collaborative note-taking
- Educational and classroom projects

Benefits
- **Fast collaboration:** Multiple people can add and refine content quickly.
- **Openness:** Transparency through revision histories and discussions.
- **Expandable:** They scale organically as users add more pages and topics.

Limitations
- **Vandalism and false information:** Open contribution can result in deliberate or accidental misinformation.
- **Inconsistent quality:** Entries may vary in accuracy, style, and completeness.
- **Organizational issues:** Without clear governance, content may become fragmented or disputed.

Notable example
- **Wikipedia** — the largest example, maintained by the Wikimedia Foundation and contributed to by volunteers worldwide.