The modern standard. It allows developers to write drivers in C that are more secure and stable; if the driver crashes, it simply restarts rather than causing a "Blue Screen of Death" (BSOD). WUDF (Windows User-Mode Driver Framework):
After upgrading from Windows 10 to 11, or after Patch Tuesday, the reader stops working. microsoft usbccid smartcard reader umdf 2 driver
Rather than forcing every hardware vendor to write a full, custom kernel driver (a crash‑risk nightmare), Microsoft provides a that works with any CCID‑compliant reader. The modern standard