# USB 2 Standard plug > the earlier class of legacy (pre-C) USB Standard plugs **Wikidata**: [Q133871730](https://www.wikidata.org/wiki/Q133871730) **Source**: https://4ort.xyz/entity/usb-2-standard-plug ## Summary The USB 2 Standard plug is a class of legacy USB connectors designed to carry USB 1.0 through USB 2.0 signals and power. It refers to the earlier generation of non-reversible "Standard" plugs—specifically the Standard-A and Standard-B types—that preceded the modern USB Type-C standard. These plugs have largely been replaced by the USB 2 Type-C plug. ## Key Facts - **Classification:** A class of legacy (pre-C) USB Standard plugs that serves as a subclass of the USB 2 Standard connector and USB 2 legacy plug. - **Variants:** Includes the **USB 2 Standard-A plug** (host end) and the **USB 2 Standard-B plug** (peripheral device end). - **Successor:** This class of plugs is technically replaced by the **USB 2 Type-C plug**. - **Capabilities:** Designed to carry only USB 1–2 data and power, distinct from later USB 3 standard plugs. - **Aliases:** Also known as the USB 1.0 Standard plug, USB 1.1 Standard plug, USB 1 Standard plug, Standard USB 2.0 plug, and Standard USB 2 plug. - **Differentiation:** Distinct from USB receptacles, Micro plugs, Mini plugs, and USB 3 Standard plugs. - **Official Name:** USB 2 Standard plug (as designated in USB Implementers Forum documents). ## FAQs ### Q: What specific plug types fall under the USB 2 Standard plug class? A: This class specifically includes the **USB 2 Standard-A plug**, used for the host connection, and the **USB 2 Standard-B plug**, used for the peripheral device end. ### Q: Is the USB 2 Standard plug still the current standard? A: No, it is considered a "legacy" class of plugs. It has been replaced by the **USB 2 Type-C plug**, which serves as the modern successor for these connections. ### Q: How does the USB 2 Standard plug differ from USB 3 plugs? A: The USB 2 Standard plug is distinct from the **USB 3 Standard plug**. While they look similar, the USB 2 version carries only USB 1–2 data and power, whereas USB 3 plugs support higher data transfer rates. ### Q: Does this class include the smaller "Mini" or "Micro" USB cables? A: No. The "USB 2 Standard plug" class is separate from **USB 2 Micro plug** and **USB Mini plug** classes, referring strictly to the full-sized Standard-A and Standard-B connectors. ## Why It Matters The USB 2 Standard plug represents the foundational hardware interface that defined peripheral connectivity for roughly two decades. As the "earlier class of legacy Standard connectors," it established the ubiquitous rectangular (Type-A) and square (Type-B) form factors that became synonymous with the word "USB" for general consumers. Its significance lies in its role as the primary bridge between computers and devices (printers, keyboards, mice, drives) during the mass adoption of the internet and personal computing. While functional, these plugs were unidirectional (could only be inserted one way) and eventually became a bottleneck for speed and size requirements. The existence of this specific class distinction is crucial for understanding the industry's shift toward the **USB 2 Type-C plug**, which was designed to replace this fragmented landscape of Standard, Mini, and Micro plugs with a single, reversible standard. ## Notable For - **Defining Legacy Connectivity:** Being the primary class of USB connectors for hosts and large peripherals prior to the Type-C transition. - **Unidirectional Design:** Unlike its successor (Type-C), these plugs are not reversible and must be inserted in a specific orientation. - **Ubiquity:** The Standard-A variant found on this class of plug became one of the most recognized and widely used ports in computing history. - **Clear Differentiation:** It is strictly defined as carrying USB 1–2 capabilities, distinguishing it from the later blue-inserted USB 3 Standard plugs. ## Body ### Definition and Hierarchy The **USB 2 Standard plug** is defined as a class of legacy plugs that preceded the USB Type-C era. It acts as a specific subclass of the broader **USB 2 Standard connector** and **USB 2 legacy plug** categories. These plugs are strictly associated with the USB 1.0, 1.1, and 2.0 eras. ### Component Types This plug class encompasses two primary specific plug types: * **USB 2 Standard-A plug:** The rectangular interface typically found on the host side (e.g., computers, gaming consoles). * **USB 2 Standard-B plug:** The squared interface typically found on the peripheral side (e.g., printers, scanners). ### Evolution and Replacement The USB 2 Standard plug is categorized as "legacy" technology. According to USB documentation, the **USB 2 Type-C plug** serves as the replacement for this class. While USB 3.0 introduced its own "Standard" plugs (often identifiable by blue plastic inserts), the USB 2 Standard plug is distinct and limited to USB 1–2 data transmission speeds and power delivery. ### Distinctions To avoid confusion with other form factors, the USB 2 Standard plug is explicitly defined as being different from: * **USB 2 Standard receptacle:** The female port on a device. * **USB 2 Micro plug & USB Mini plug:** Smaller form factors used for mobile devices. * **USB 3 Standard plug:** The backward-compatible but technically distinct high-speed successor. ## 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)