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.

Main features
- **Collaborative editing:** Numerous contributors can work on pages, sometimes simultaneously.
- **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:** 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:** Dedicated discussion pages enable contributors to coordinate and discuss content.

Typical uses
- Community-driven knowledge bases (for example, Wikipedia)
- Project documentation and internal company knowledge repositories
- 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.

Cons
- **Vandalism and false information:** Public editing can lead to vandalism or incorrect information.
- **Inconsistent quality:** Content quality may vary widely between pages.
- **Organizational issues:** Lack of structure or rules can lead to disorganization and conflicts.

Illustration
- **Wikipedia** — the largest example, maintained by the Wikimedia Foundation and contributed to by volunteers worldwide.