PCIe (PCI Express)
Beginner
The standard kind of super-fast wiring that joins the parts inside a computer to its processor.
Novice
A point-to-point serial link standard. Each link is made of one or more lanes; each new generation doubles the data rate per lane while staying compatible with older devices.
Expert
A load-store interconnect with a layered protocol (transaction, data link, physical). Generations 1–5 used NRZ signaling with 8b/10b or 128b/130b coding; 6.0 and 7.0 use PAM4 and fixed 256-byte flits with FEC. Links negotiate width and rate down to what both ends support.