# Micro-USB > a class of legacy USB connectors that preceded USB-C, along with Standard and Mini **Wikidata**: [Q1931429](https://www.wikidata.org/wiki/Q1931429) **Wikipedia**: [English](https://en.wikipedia.org/wiki/Micro-USB) **Source**: https://4ort.xyz/entity/micro-usb ## Summary Micro-USB is a class of legacy USB connectors that preceded the modern USB-C standard, serving alongside Standard and Mini connectors. Developed and published by the USB Implementers Forum, this connector class was designed to replace the older Mini-USB interface. It includes various specific plug and receptacle types, such as Micro-A, Micro-B, and Micro-AB, which have largely been phased out in favor of USB-C. ## Key Facts * **Classification:** Micro-USB is a subclass of "legacy USB connectors," a category encompassing all USB types preceding USB-C. * **Succession:** It replaces the **Mini-USB** standard and has been effectively replaced by **USB-C**. * **Publisher:** The standard is managed and published by the **USB Implementers Forum**. * **Official Name:** While commonly known as Micro-USB, the official designation is **USB Micro connector**. * **Variants:** The class includes distinct subtypes, such as the **USB Micro-A plug** (host end), **USB Micro-B connector** (peripheral device end), and **USB Micro-AB receptacle** (which accepts both Type-A and Type-B plugs). * **Technology Versions:** The class includes **USB 2 Micro connectors** (carrying USB 1–2 signals and power) and **USB 3 Micro connectors** (a latter class of legacy Micro connectors). * **Differentiation:** It is structurally and functionally distinct from USB-C, USB Standard connectors, and Mini-USB. ## FAQs ### Q: What is the difference between Micro-USB and USB-C? A: Micro-USB is a legacy connector class that preceded USB-C. While Micro-USB includes multiple distinct plug types (like Micro-A and Micro-B) with specific orientations, USB-C was developed to replace all these legacy connectors with a single, reversible standard. ### Q: What types of devices used Micro-USB? A: Micro-USB connectors were used for both host and peripheral devices. The Micro-A plug was designed for the host end, while the Micro-B connector was designed for the peripheral device end. ### Q: What did Micro-USB replace? A: Micro-USB replaced the Mini-USB standard. It served as a smaller, more durable alternative for mobile and compact devices before the advent of USB-C. ## Why It Matters Micro-USB represents a critical phase in the evolution of universal connectivity. Before the widespread adoption of USB-C, Micro-USB served as the predominant interface for mobile devices, external storage, and various peripherals. Its development by the USB Implementers Forum marked a shift towards smaller, more robust connector designs capable of handling increased power and data requirements compared to the preceding Mini-USB. The standard's significance lies in its attempt to unify device connectivity through various form factors like Micro-A and Micro-B, and the versatile Micro-AB receptacle. Although it is now classified as a "legacy" technology replaced by the USB-C ecosystem, Micro-USB remains one of the most recognized connector shapes in computing history. It bridged the gap between early USB implementations and the modern, reversible Type-C standard, facilitating the miniaturization of electronics. ## Notable For * **Legacy Classification:** It is officially classified as a "legacy" connector type, distinct from the modern USB-C standard that replaces it. * **Versatile Receptacles:** The **USB Micro-AB receptacle** was notable for its ability to accept both Type-A and Type-B plugs, a feature intended to increase device compatibility. * **Succession of Mini-USB:** It successfully replaced the larger Mini-USB connectors, enabling the design of slimmer electronic devices. * **Defined Sub-classes:** It introduced distinct classes for **USB 2** and **USB 3** iterations, allowing for higher data transfer speeds within the same physical form factor family. ## Body ### Classification and Definition The **Micro-USB**, officially termed the **USB Micro connector**, is a class of legacy USB connectors. It falls under the broader umbrella of connectors that preceded the USB-C (Type-C) standard. Unlike USB-C, which serves as a universal replacement, Micro-USB existed alongside Standard and Mini connectors during its operational lifespan. It is distinct from these other form factors and is managed by the USB Implementers Forum. ### Connector Types and Variants The Micro-USB standard encompasses several specific plugs and receptacles designed for different functions: * **USB Micro-A plug:** A class of legacy plugs designed for the host end of a connection. * **USB Micro-B connector:** A class designed for the peripheral device end. * **USB Micro-AB receptacle:** A legacy receptacle notable for accepting both Type-A and Type-B plugs, indicated by the "AB" designation. * **USB Micro plug:** The general class of plugs preceding USB-C. These components are visually documented in technical illustrations (e.g., *USB connector illustration, to scale, grouping, legacy, Micro.svg*) which depict the scale and grouping of these legacy interfaces. ### Technical Evolution The Micro-USB class evolved through two primary technical phases: 1. **USB 2 Micro connector:** This class carried USB 1–2 signals and power. It was eventually replaced by USB 2 Type-C connectors. 2. **USB 3 Micro connector:** This represents the latter class of legacy Micro connectors, offering improved performance before the transition to USB-C. ### Replaced and Replacing In the timeline of USB development, Micro-USB sits between the Mini-USB and USB-C eras. It explicitly **replaces Mini-USB** and has subsequently been **replaced by USB-C**. The shift to USB-C was driven by the need for a universal connector that could supersede the various "legacy" shapes (Standard, Mini, and Micro) defined in earlier specifications. ## 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/usb-type-cr-cable-and-connector-specification-release-24) 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/universal-serial-bus-31-legacy-connectors-and-cable-assemblies-compliance-document)