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.

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:** 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:** Wikis may allow public editing or restrict changes to registered or authorized users.
- **Discussion pages:** Talk or discussion pages let contributors debate edits and organization.

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

Pros
- **Fast collaboration:** Multiple people can add and refine content quickly.
- **Openness:** Transparency through revision histories and discussions.
- **Expandable:** Wikis expand easily as contributors add and organize content.

Limitations
- **Vandalism and false information:** Open editing may allow intentional or accidental inaccuracies.
- **Inconsistent quality:** Entries may vary in accuracy, style, and completeness.
- **Organizational issues:** Lack of structure or rules can lead to disorganization and conflicts.

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