USB-C

USB‑C, or USB Type‑C, is a 24-pin reversible connector that supersedes all previous USB connectors, which were designated legacy in 2014. This connector also supersedes Mini DisplayPort and Lightning connectors. USB-C is used for a variety of purposes: exchanging data with peripheral devices, such as external drives, mobile phones, keyboards, track-pads, and mice, or between hosts, or transferring A/V-data to displays and speakers, or also powering peripheral devices and getting powered by power adapters; either through directly wired connectors, or indirectly via hubs and docking stations. This connector type can be used for other data transfer protocols besides USB, such as Thunderbolt, PCIe, DisplayPort, and HDMI. It is considered extensible, allowing the support of future protocols.
The design for the USB‑C connector was initially developed in 2012 by Intel, Apple Inc., HP Inc., Microsoft, and the USB Implementers Forum. The Type‑C Specification 1.0 was published by the USB Implementers Forum on August 11, 2014. In 2016 it was adopted by the IEC as "IEC 62680-1-3".
The USB Type‑C connector has 24 pins and is reversible. The designation C distinguishes it from the various USB connectors it replaced, all termed either Type‑A or Type‑B. Whereas earlier USB cables had a host end A and a peripheral device end B, a USB‑C cable connects either way; and for interoperation with older equipment, there are cables with a Type‑C plug at one end and either a Type‑A or a Type‑B plug at the other.
The designation C refers only to the connector's physical configuration, or form factor, not to be confused with the connector's specific capabilities and performance, such as Thunderbolt 3, DisplayPort 2.0, USB 3.2 Gen 2×2. While USB‑C is the single modern connector for all USB protocols, there are valid uses of the connector that do not involve any USB protocol. Based on the protocols supported by all, host, intermediate devices, and peripheral devices, a USB‑C connection normally provides much higher data rates, and often more electrical power, than anything using the superseded connectors.
A device with a Type‑C connector does not necessarily implement any USB transfer protocol, USB Power Delivery, or any of the Alternate Modes: the Type‑C connector is common to several technologies while mandating only a few of them.
USB 3.2, released in September 2017, fully replaced the USB 3.1 specifications. It preserves the former USB 3.1 SuperSpeed and SuperSpeed+ data transfer modes and introduces two additional data transfer modes by newly applying two-lane operations, with signalling rates of 10 Gbit/s and 20 Gbit/s. They are only applicable with Full-Featured USB‑C cables and connectors and hosts, hubs, and peripheral devices that use them.
USB4, released in 2019, is the first USB transfer protocol standard that is applicable exclusively via USB‑C.

Ease of use

The USB‑C standard simplifies usage by specifying cables having identical plugs on both ends, which can be inserted without concern about orientation. When connecting two devices, the user can plug either end of the cable into either device. The plugs are flat, but will work if inserted right-side-up or upside-down.
The USB‑C receptacles have two-fold rotational symmetry because a plug may be inserted into a receptacle in either of two orientations. Electrically, USB‑C plugs are not symmetric, as can be seen in the tables of pin layouts. Also, the two ends of the USB‑C are electrically different, as can be seen in the table of cable wiring. The illusion of symmetry results from how devices respond to the cable. Software makes the plugs and cables behave as though they are symmetric. According to the specifications, "Determination of this host-to-device relationship is accomplished through a Configuration Channel that is connected through the cable."
The USB‑C standard attempts to eliminate the need to have different cables for other communication technologies, such as Thunderbolt, PCIe, HDMI, DisplayPort and more. Over the past decade since 2014, many companies including Samsung Electronics, Apple Inc. and Transsion have adopted the USB‑C standard into their products. USB‑C cables can contain circuit boards and processors giving them much more capability than simple circuit connections.

Overview

USB‑C cables interconnect hosts and peripheral devices, replacing various other electrical cables and connectors, including all earlier USB connectors, HDMI connectors, DisplayPort ports, and 3.5 mm audio jacks.

Name

USB Type‑C and USB‑C are trademarks of the USB Implementers Forum.

Connectors

The 24-pin double-sided connector is slightly larger than the non-SuperSpeed, USB 2.0 Micro connectors, with a USB‑C receptacle opening measuring 8.34mm× 2.56mm, 6.20mm deep.

Cables

Type‑C cables can be split among various categories and subcategories. The first one is USB 2.0 vs Full-Featured. USB 2.0 Type‑C cables have very limited wires and are only good for USB 2.0 communications and power delivery. They are also called charging cables colloquially. Conversely, Full-Featured cables need to have all wires populated and in general support Alt modes and are further distinguished by their speed rating.
Full-Featured cables exist in four different speed grades. Their technical names use the "Gen A" notation, each higher number increasing capabilities in terms of bandwidth. The user-facing names are based on the bandwidth a user can typically expect "USB 5Gbps", "USB 20Gbps", "USB 40Gbps" and so on. This bandwidth notation considers the various USB standards and how they use the cable. A Gen 1 / 5 Gbit/s cable supports that bandwidth on every one of its 4 wire pairs. So technically it could be used to establish a USB 3 Gen 1x2 connection with nominally 10 Gbit/s between two "SuperSpeed USB 20 Gbps" capable hosts. For a similar reason, the "USB 10Gbps" name is deprecated, as that is using only 2 of the 4 wire-pairs of a Gen 2 cable and thus synonymous with "USB 20Gbps" cables. The signal quality that the "Gen A" notation guarantees or requires is not uniform across all USB standards. See table for details.
The USB Implementers Forum certifies valid cables so they can be marked accordingly with the official logos and users can distinguish them from non-compliant products. There have been simplifications in the logos. Previous logos and names also referenced specific USB protocols like SuperSpeed for the USB 3 family of connections or USB4 directly. The current official names and logos have removed those references as most full-featured cables can be used for USB4 connections as well as USB 3 connections.
In order to achieve longer cable lengths, cable variants with active electronics to amplify the signals also exist. The Type‑C standard mostly mandates these active cables to behave similarly to passive cables with vast backwards compatibility, but they are not mandated to support all possible features and typically have no forward compatibility to future standards. Optical cables are even allowed to further reduce the backwards compatibility. For example, an active cable may not be able to use all high speed wire-pairs in the same direction, but only in the symmetric combinations expected by classic USB connections. Passive cables have no such limitations.

Power delivery

Every USB‑C cable must support at least 3 amps of current and up to 20 volts for up to 60 watts of power according to the USB PD specification. Cables were also allowed to support up to 5 A while retaining the 20 V limit, allowing up to 100 W of power; however, the 20 V limit for 5 A cables has been deprecated in favor of 48 V. The combination of higher voltage support and 5 A current support is called Extended Power Range and allows for up to 240 W of power according to the USB PD specification.

E-Marker

All Type‑C cables except the minimal combination of USB 2.0 and only 3 A must contain E-Marker chips that identify the cable and its capabilities via the USB PD protocol. This identification data includes information about product/vendor, cable connectors, USB signalling protocol, passive/active construction, use of V_CONN power, available V_BUS current, latency, RX/TX directionality, SOP controller mode, and hardware/firmware version. It also can include further vendor-defined messages that detail support for Alt modes or vendor-specific functionality outside of the USB standards.

Cable types

Hosts and peripheral devices

For any two pieces of equipment connecting over USB, one is a host and the other is a peripheral device. Some products, such as mobile phones, can take either role, whichever is opposite that of the connected equipment. Such equipment is said to have Dual-Role-Data capability, which was known as USB On-The-Go in the previous specification. With USB‑C, when two such devices are connected, the roles are first randomly assigned, but a swap can be commanded from either end, although there are optional path and role detection methods that would allow equipment to select a preference for a specific role. Furthermore, Dual-Role equipment that implements USB Power Delivery may swap data and power roles independently using the Data Role Swap or Power Role Swap processes. This allows for charge-through hub or docking station applications such as a portable computer acting as a host to connect to peripherals but being powered by the dock, or a computer being powered by a display, through a single USB‑C cable.
USB‑C devices may optionally provide or consume bus power currents of 1.5 A and 3.0 A in addition to baseline bus power provision; power sources can either advertise increased USB current through the configuration channel or implement the full USB Power Delivery specification using both the BMC-coded configuration line and the legacy BFSK-coded V_BUS line.
All older USB connectors are designated legacy. Connecting legacy and modern, USB‑C equipment requires either a legacy cable assembly or, in very specific cases, a legacy adapter assembly.
An older device can connect to a modern host by using a legacy cable, with a Standard-B, Mini-B, or Micro-B plug on the device end and a USB‑C plug on the other. Similarly, a modern device can connect to a legacy host by using a legacy cable with a USB‑C plug on the device end and a Standard-A plug on the host end. Legacy adapters with USB‑C receptacles are "not defined or allowed" by the specification because they can create "many invalid and potentially unsafe" cable combinations. However, exactly two types of USB adapters with Type‑C plugs are defined: An adapter with a Standard‑A receptacle, and one with a Micro‑B receptacle.