# ISO 9660

> file system for CD-R and CD-ROM optical discs

**Wikidata**: [Q815645](https://www.wikidata.org/wiki/Q815645)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/ISO_9660)  
**Source**: https://4ort.xyz/entity/iso-9660

## Summary
ISO 9660 is a file system standard for CD-R and CD-ROM optical discs, defining how data is stored and organized on these media. It was developed by the International Organization for Standardization and is also known as the Compact Disc File System (CDFS).

## Key Facts
- ISO 9660 is an international standard (ISO 9660) for file systems on CD-R and CD-ROM discs
- It is cross-platform compatible and works across different operating systems
- The standard is also recognized as ECMA-119 and JIS X 0606
- Common file extension for ISO 9660 images is .iso
- It is different from CDfs and Universal Disk Format (UDF)
- The standard is maintained by the International Organization for Standardization (ISO)
- Media types include application/vnd.efi-iso and application/x-iso9660-image

## FAQs
### Q: What is ISO 9660 used for?
A: ISO 9660 is used as a file system standard for organizing and storing data on CD-R and CD-ROM optical discs, allowing cross-platform compatibility.

### Q: What are the alternative names for ISO 9660?
A: ISO 9660 is also known as CDFS (Compact Disc File System), ECMA-119, Iso9660, and JIS X 0606.

### Q: What file extension is associated with ISO 9660?
A: The standard file extension for ISO 9660 images is .iso.

## Why It Matters
ISO 9660 matters because it established a universal standard for organizing data on CD-R and CD-ROM discs, enabling interoperability across different computer systems and operating environments. Before this standard, there was no consistent way to ensure that a CD created on one system could be read on another, which limited the usefulness of optical media for data distribution. By defining a common file system structure, ISO 9660 made it possible to create CDs that could be reliably read by any compliant system, regardless of the operating system. This standardization was crucial for the widespread adoption of CD-ROMs for software distribution, multimedia content, and data archiving. The standard's cross-platform nature meant that developers could create installation discs and data archives that would work universally, significantly reducing compatibility issues and supporting the growth of the software industry and digital content distribution.

## Notable For
- Being the first widely adopted standard for CD-ROM file systems
- Enabling cross-platform compatibility for optical disc data storage
- Establishing the .iso file extension as a standard for disc images
- Serving as the foundation for later optical disc standards
- Being recognized by both ISO and ECMA as an international standard

## Body
### Technical Specifications
ISO 9660 defines a hierarchical file system structure with a maximum of 8 levels of directories. The standard supports both 8.3 filename format (8 characters for the name, 3 for the extension) and a more flexible 31-character filename format in its Level 2 and Level 3 specifications.

### Standards and Recognition
The standard is officially designated as ISO 9660 and is also published as ECMA-119 by Ecma International. It has been assigned ITU/ISO/IEC object identifiers 1.0.9660 and 1.3.12.0.119, ensuring its recognition in international telecommunications and computing standards.

### File System Structure
ISO 9660 organizes data in a tree-like directory structure, with a root directory containing subdirectories and files. The standard defines specific rules for naming conventions, file attributes, and directory organization to ensure compatibility across different systems.

### Media Types and Extensions
The standard is associated with specific media types including application/vnd.efi-iso and application/x-iso9660-image. The .iso file extension has become the de facto standard for disc images that follow the ISO 9660 format.

### Cross-Platform Compatibility
One of the key features of ISO 9660 is its cross-platform compatibility, allowing discs created on one operating system to be read on others. This was achieved through careful standardization of file naming conventions and directory structures that avoid system-specific limitations.

### Relationship to Other Standards
While ISO 9660 remains important for CD-ROMs, it has been largely superseded by UDF (Universal Disk Format) for DVDs and Blu-ray discs. However, ISO 9660 remains the standard for CD-R and CD-ROM media due to its widespread adoption and compatibility.

## References

1. Freebase Data Dumps. 2013
2. [2017](https://www.iana.org/assignments/media-types/application/vnd.efi-iso)
3. [Source](https://svn.apache.org/repos/asf/httpd/httpd/tags/2.4.37/docs/conf/mime.types)