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.

Common 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:** 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:** Access controls vary — from fully open editing to permissions for certain users or groups.
- **Discussion pages:** Separate talk pages allow contributors to discuss edits and structure.

Typical uses
- Crowd-sourced knowledge resources (e.g., Wikipedia)
- Internal documentation and company knowledge bases
- Group writing and collaborative note-taking
- School and instructional projects

Pros
- **Fast collaboration:** Multiple people can add and refine content quickly.
- **Openness:** Visibility into edits and discussions shows how decisions were reached.
- **Expandable:** Wikis expand easily as contributors add and organize content.

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