What does the X4 mean in an PCIe Gen X4 NVME drive?

Hyper x16 Gen 4 Card｜Motherboards｜ASUS Global nvme gen 4 in gen 3 slot Next Generation Storage：3*PCIe x4 Connectors; Advanced Thermal Ultra-Fast Storage：4* slots, including 3* PCIe x4; Efficient Overall nvme pcie slot There seem to be some Gen 4 x4 NVMe 2230 M 1) The HAT is Gen 3 and I read that Gen 4 is backwards compatible, but at Gen 3 speeds Are Gen4 drives backwards

nvme vs m2 slot difference 2 NVMe SSDs are backward-compatible, so even with a Gen3 platform, you usually get better value from a Gen4 SSD even if it can't run at its rated speed