# GUID Partition Table

> standard for the layout of the partition table on a physical storage device used in a desktop or server PC

**Wikidata**: [Q603889](https://www.wikidata.org/wiki/Q603889)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/GUID_Partition_Table)  
**Source**: https://4ort.xyz/entity/guid-partition-table

## Summary
The GUID Partition Table (GPT) is a standard disk partitioning scheme used to define the layout of partitions on physical storage devices for desktop and server PCs. It serves as a core component of the Unified Extensible Firmware Interface (UEFI) specification, defining how an operating system interfaces with platform firmware regarding disk metadata. GPT utilizes Universally Unique Identifiers (UUIDs) to specify the location, size, and identity of partitions.

## Key Facts
- **Classification:** GPT is a disk partitioning scheme and a subclass of the partition table category.
- **Specification:** It is a formal part of the Unified Extensible Firmware Interface (UEFI) specification.
- **Identification Method:** The system uses Universally Unique Identifiers (UUIDs) for partition and disk identification.
- **Primary Documentation:** Detailed in the UEFI Specification, Version 2.8, specifically under Section 5: "GUID Partition Table (GPT) Disk Layout."
- **Preceded By:** GPT succeeded the Apple Partition Map (APM) partitioning scheme.
- **Usage:** Standardized for the layout of physical storage devices in both desktop and server environments.
- **Common Aliases:** Frequently referred to as GPT, GUID-Partitionstabelle, and GUID磁碟分割表.

## FAQs
### Q: What is the primary function of the GUID Partition Table?
A: GPT is an on-disk format used to specify the location, size, and metadata of partitions on a physical storage device. It provides a standard layout that allows operating systems to manage disk space on desktop and server PCs.

### Q: How does GPT relate to UEFI?
A: GPT is a specific part of the Unified Extensible Firmware Interface (UEFI) specification. It defines the software interface between the platform firmware and the operating system for storage device partitioning.

### Q: What makes GPT different from older partitioning schemes?
A: Unlike older schemes, GPT uses Universally Unique Identifiers (UUIDs) to identify partitions. It also succeeded the Apple Partition Map (APM) to become the standard for modern UEFI-based systems.

## Why It Matters
The GUID Partition Table (GPT) is essential for modern computing as it provides the standardized framework for how storage devices are organized and accessed. By serving as a critical component of the Unified Extensible Firmware Interface (UEFI), it ensures compatibility between hardware firmware and various operating systems. 

The transition to GPT solved limitations found in earlier partitioning methods, such as the Apple Partition Map. Its use of Universally Unique Identifiers (UUIDs) allows for a more robust and globally unique method of identifying disk partitions, which is vital for data integrity and system stability in complex server and desktop environments. As the industry standard documented in the UEFI Specification, GPT is the foundational technology that enables modern systems to recognize and boot from large-scale physical storage devices.

## Notable For
- **UEFI Integration:** It is the standard partitioning scheme defined by the Unified Extensible Firmware Interface specification.
- **UUID Implementation:** Employs Universally Unique Identifiers to ensure every partition and disk has a unique identity.
- **Industry Standard:** Recognized as the primary successor to the Apple Partition Map (APM) for physical storage layout.
- **Extensive Documentation:** Formally standardized in technical resources like the UEFI Specification Version 2.8 and the Gentoo Wiki.

## Body

### Technical Definition and Classification
The GUID Partition Table (GPT) is an on-disk format used for specifying the location, size, and metadata of partitions on physical storage. It is classified as a disk partitioning scheme and is a subclass of the partition table. GPT is a fundamental facet of operating system functionality, particularly regarding how software interacts with physical storage hardware.

### Relationship to UEFI
GPT is a constituent part of the Unified Extensible Firmware Interface (UEFI). The UEFI specification defines the software interface between an operating system and platform firmware. Within this framework, GPT provides the specific disk layout required for the firmware to identify bootable partitions and manage storage metadata.

### Identification via UUID
A core technical feature of GPT is its use of the Universally Unique Identifier (UUID). This system ensures that partitions are identified by a unique string, reducing the likelihood of identifier collisions between different devices or systems. This metadata is essential for the operating system to correctly map and mount storage volumes.

### Standards and Documentation
The technical requirements for GPT are maintained in several key industry documents:
*   **UEFI Specification:** Version 2.8, Section 5, titled "GUID Partition Table (GPT) Disk Layout," provides the definitive technical standard.
*   **Historical Context:** GPT succeeded the Apple Partition Map (APM) as the preferred partitioning scheme for modern computing.
*   **Cross-Platform Support:** It is documented across various technical platforms, including the Gentoo Wiki and Microsoft Academic records, and is supported by tools such as GNU Parted.

## References

1. Freebase Data Dumps. 2013