A wiki is a website designed for collaborative editing, letting many people create, update, and organize content directly in a web 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:** Creating links among pages is straightforward, which helps interconnect content.
- **Lightweight markup:** Formatting is usually handled by lightweight markup languages (e.g., WikiText or Markdown).
- **Permission settings:** Access controls vary — from fully open editing to permissions for certain users or groups.
- **Discussion pages:** Talk or discussion pages let contributors debate edits and organization.

Typical uses
- Crowd-sourced knowledge resources (e.g., Wikipedia)
- Project documentation and internal company knowledge repositories
- Collaborative writing and shared note-taking
- Educational and classroom projects

Benefits
- **Fast collaboration:** Many people can collaborate and iterate quickly on content.
- **Openness:** Visibility into edits and discussions shows how decisions were reached.
- **Expandable:** Wikis can grow naturally as contributors add new topics.

Drawbacks
- **Vandalism and false information:** Public editing can lead to vandalism or incorrect information.
- **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** — the best-known wiki, run by the Wikimedia Foundation and built by volunteer contributors worldwide.