The jargon, decoded
USB-C & Thunderbolt glossary
The terms that actually decide what a cable can do — in plain words.
| Term | In one line |
|---|---|
| E-marker | The chip inside a USB-C cable that reports its real capabilities. |
| USB Power Delivery (USB-PD) | The protocol USB-C devices use to negotiate charging power. |
| Extended Power Range (EPR, 240 W) | The USB-PD tier that lifts charging from 100 W to 240 W. |
| Thunderbolt 4 | A strict superset of USB4 — guaranteed 40 Gbps, PCIe, dual-4K. |
| Thunderbolt 5 | 80 Gbps symmetric, up to 120 Gbps for displays, more power. |
| USB4 | The USB-C data standard — 20 or 40 Gbps, with optional features. |
| DisplayPort Alt Mode | How a USB-C cable carries a monitor's video signal. |
| VDO (Vendor Defined Object) | The 32-bit record encoding a cable's identity and capabilities. |
| USB-IF (USB Implementers Forum) | The body that defines USB standards and registers vendor IDs. |
| PDO (Power Delivery Object) | One power profile a charger offers during USB-PD negotiation. |
| SOP' (cable plug identity) | The channel USB-C uses to read the cable's own e-marker. |
| UHBR (Ultra High Bit Rate) | The DisplayPort 2.x link rates above HBR3. |
| Active vs. passive cable | Why some USB-C cables carry high speeds over longer lengths. |