Wikis are websites built for collaborative authoring, allowing numerous contributors to add, edit, and structure content online.

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.

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:** Some wikis are open to anyone; others limit edits to registered users or specific groups.
- **Discussion pages:** Dedicated discussion pages enable contributors to coordinate and discuss content.

Frequent uses
- Community-driven knowledge bases (for example, Wikipedia)
- Internal documentation and company knowledge bases
- Cooperative writing and shared notes
- School and instructional projects

Pros
- **Fast collaboration:** Multiple people can add and refine content quickly.
- **Openness:** Edit histories and talk pages reveal how content decisions were made.
- **Expandable:** They scale organically as users add more pages and topics.

Limitations
- **Vandalism and false information:** Open contribution can result in deliberate or accidental misinformation.
- **Inconsistent quality:** Entries may vary in accuracy, style, and completeness.
- **Organizational issues:** Poor coordination or governance can cause content fragmentation and disputes.

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