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

They emphasize simplicity and openness — pages can be created or modified without special technical skills, and most maintain an edit history so revisions can be reviewed or reverted.

Common features
- **Collaborative editing:** Several contributors can edit pages, sometimes at the same time.
- **Edit history:** Every modification is recorded with a timestamp and the editor’s identity or IP address.
- **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:** Dedicated discussion pages enable contributors to coordinate and discuss content.

Common uses
- Community-driven knowledge bases (for example, Wikipedia)
- Internal documentation and company knowledge bases
- Cooperative writing and shared notes
- Educational and classroom projects

Advantages
- **Fast collaboration:** Multiple people can add and refine content quickly.
- **Openness:** Edit histories and talk pages reveal how content decisions were made.
- **Expandable:** Wikis expand easily as contributors add and organize content.

Drawbacks
- **Vandalism and false information:** Public editing can lead to vandalism or incorrect information.
- **Inconsistent quality:** Content quality may vary widely between pages.
- **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.