A wiki is a website designed for collaborative editing, letting many people create, update, and organize content directly in a web 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.

Common features
- **Collaborative editing:** Multiple people can edit the same pages, occasionally concurrently.
- **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:** 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:** Separate talk pages allow contributors to discuss edits and structure.

Typical uses
- Crowd-sourced knowledge resources (e.g., Wikipedia)
- Project documentation and internal company knowledge repositories
- Cooperative writing and shared notes
- School and instructional projects

Pros
- **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.

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:** Lack of structure or rules can lead to disorganization and conflicts.

Example
- **Wikipedia** — the best-known wiki, run by the Wikimedia Foundation and built by volunteer contributors worldwide.