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

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:** 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:** Pages are typically formatted with lightweight markup like WikiText or Markdown.
- **Permission settings:** Some wikis are open to anyone; others limit edits to registered users or specific groups.
- **Discussion pages:** Separate talk pages allow contributors to discuss edits and structure.

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

Pros
- **Fast collaboration:** Contributors can rapidly create and improve content.
- **Openness:** Transparency through revision histories and discussions.
- **Expandable:** Wikis can grow naturally as contributors add new topics.

Limitations
- **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:** Poor coordination or governance can cause content fragmentation and disputes.

Notable example
- **Wikipedia** — a well-known wiki operated by the Wikimedia Foundation and written by volunteers around the globe.