NVMe drive
Beginner
A fast storage drive, like the one in a laptop, that plugs straight into the processor’s fast wires.
Novice
NVM Express: the standard way a computer talks to solid-state (flash) drives over PCIe. Data-center NVMe drives usually use four PCIe lanes each.
Expert
A queue-based command protocol (many deep submission/completion queues) over PCIe, RDMA or TCP. Form factors include U.2, M.2 and EDSFF E1.S/E3.S; an E3 1C connector carries x4, a 2C connector x8.
Explained in Board and server (Systems).