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.

Main 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:** Creating links among pages is straightforward, which helps interconnect 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.

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

Advantages
- **Fast collaboration:** Many people can collaborate and iterate quickly on content.
- **Openness:** Transparency through revision histories and discussions.
- **Expandable:** They scale organically as users add more pages and topics.

Drawbacks
- **Vandalism and false information:** Open contribution can result in deliberate or accidental misinformation.
- **Inconsistent quality:** Articles can differ greatly in depth, tone, and reliability.
- **Organizational issues:** Poor coordination or governance can cause content fragmentation and disputes.

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