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.

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:** It’s easy to create links between pages, forming an interconnected knowledge base.
- **Lightweight markup:** Simple markup languages (such as WikiText or Markdown) are used to format pages.
- **Permission settings:** Some wikis are open to anyone; others limit edits to registered users or specific groups.
- **Discussion pages:** Talk or discussion pages let contributors debate edits and organization.

Common uses
- Community-driven knowledge bases (for example, Wikipedia)
- Internal documentation and company knowledge bases
- Group writing and collaborative note-taking
- Classroom and educational projects

Advantages
- **Fast collaboration:** Many people can collaborate and iterate quickly on content.
- **Openness:** Transparency through revision histories and discussions.
- **Expandable:** Wikis can grow naturally as contributors add new topics.

Limitations
- **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:** Without clear governance, content may become fragmented or disputed.

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