# USB Micro receptacle > a class of legacy USB receptacles that preceded USB-C, along with Standard and Mini **Wikidata**: [Q133871429](https://www.wikidata.org/wiki/Q133871429) **Source**: https://4ort.xyz/entity/usb-micro-receptacle ## Summary The USB Micro receptacle is a class of legacy USB connectors that served as the standard interface for mobile and peripheral devices prior to the introduction of USB-C. It was designed to replace the bulkier USB Mini receptacle and includes variants such as Micro-B and Micro-AB. As a legacy component, it has been functionally superseded by the USB Type-C receptacle. ## Key Facts * **Classification:** The USB Micro receptacle is a subclass of both "Micro-USB" and "legacy USB receptacle." * **Succession:** It replaced the USB Mini receptacle as the standard for mobile connectivity. * **Obsolescence:** It is categorized as a "legacy" connector because it preceded and was subsequently replaced by USB-C. * **Variants:** The class includes distinct sub-types, specifically the USB Micro-B receptacle (for peripheral devices) and the USB Micro-AB receptacle (which accepts both Type-A and Type-B plugs). * **Generations:** The technology is divided into USB 2 Micro receptacles (carrying USB 1–2 signals and power) and USB 3 Micro receptacles. * **Official Name:** USB Micro receptacle (standardized by USB Implementers Forum). * **Differentiation:** Distinct from the USB Micro plug, USB Standard receptacle, and USB Mini receptacle. ## FAQs ### Q: What is the difference between a USB Micro receptacle and a USB-C receptacle? A: The USB Micro receptacle is a legacy connector class that preceded USB-C. While USB Micro was the standard for many years, the USB-C receptacle was introduced to replace it and all other legacy USB form factors. ### Q: What devices used the USB Micro receptacle? A: This receptacle class was commonly used on the "peripheral device end" (Type-B) of cables, connecting to devices such as smartphones, external hard drives, and other electronics before USB-C became standard. ### Q: What is the difference between Micro-B and Micro-AB receptacles? A: A USB Micro-B receptacle is designed specifically for peripheral devices, whereas a USB Micro-AB receptacle is designed to accept both Type-A and Type-B plugs, often allowing the host device to act as either the host or the peripheral. ## Why It Matters The USB Micro receptacle represents a critical phase in the evolution of connectivity, serving as the ubiquitous standard for mobile and portable devices during the transition from the early 2000s to the mid-2010s. Before the advent of the reversible and universal USB-C, the USB Micro receptacle solved the need for a slimmer, more durable connection compared to its predecessor, the USB Mini. This form factor enabled the shrinking of device profiles, facilitating the development of thinner smartphones and tablets. The existence of specific sub-classes, such as the USB 3 Micro receptacle, also highlights the era's need to balance high-speed data transfer with compact physical footprints. Although now considered "legacy" and officially replaced by the USB 2 Type-C and USB 3.2 Type-C standards, billions of devices retaining these ports remain in circulation. Understanding this receptacle is essential for maintaining legacy hardware and comprehending the design shifts that led to the modern, universal USB-C standard. ## Notable For * **Predecessor to USB-C:** Being the final major proprietary shape before the industry converged on the USB-C standard. * **Form Factor:** Offering a significantly smaller profile than the previous USB Mini and USB Standard receptacles. * **Versatility:** Introducing the Micro-AB variant, which allowed a single port to accept different plug orientations (Type-A and Type-B). * **Ubiquity:** Serving as the dominant charging and data port for the majority of non-Apple smartphones and accessories for over a decade. ## Body ### Classification and Hierarchy The USB Micro receptacle is a defined class within the USB hardware taxonomy. It acts as a parent class to several specific implementations: * **USB 2 Micro receptacle:** Designed to carry USB 1–2 data and power. This class is specifically replaced by the USB 2 Type-C receptacle in modern standards. * **USB 3 Micro receptacle:** A later class of legacy Micro receptacles designed for higher data throughput, preceding the USB-C transition. * **USB Micro-B receptacle:** The standard peripheral-side connector, distinguishable by its distinct trapezoidal shape (in USB 2) or stacked connector (in USB 3). * **USB Micro-AB receptacle:** A specialized receptacle that allows the connection of both Type-A and Type-B Micro plugs. ### Technical Definition and Standards Officially named "USB Micro receptacle," this component is distinct from the "USB Micro plug" (the cable end). It is legally and technically defined as a "legacy USB receptacle," a category encompassing all USB receptacles other than Type-C. According to USB-IF documentation (including USB 3.1 Legacy Cable and Connector revisions and USB 3.2 specifications), these receptacles are part of a class that has been superseded. The "Micro" designation refers to the physical scale of the interface, which was necessitated by the miniaturization of consumer electronics. ### Visual Identification Visually, USB Micro receptacles are characterized by their thin, rectangular profiles with tapered corners (specifically Micro-B) to ensure correct orientation. The USB 3 variants are slightly taller to accommodate additional pins for higher speeds. Visual documentation of these legacy connectors is maintained under the "USB Micro receptacles" commons category. ## References 1. [Source](https://www.usb.org/document-library/usb-31-legacy-cable-and-connector-revision-10) 2. [Source](https://www.usb.org/document-library/universal-serial-bus-31-legacy-connectors-and-cable-assemblies-compliance-document) 3. [Source](https://www.usb.org/document-library/usb-32-revision-11-june-2022) 4. [Source](https://www.usb.org/document-library/usb-type-cr-connectors-and-cable-assemblies-compliance-document-rev-21b) 5. [Source](https://www.usb.org/document-library/usb-type-cr-cable-and-connector-specification-release-24)