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

What does the X4 mean in an PCIe Gen X4 NVME drive? can i use m 2 pcie 4 0 in 3 0 slot PCI Express Specification Revision , Version , This proposal will allow PCIe and SATA to be delivered using a BGA package can i use gen 4 ssd on gen 3 slot PCI Express Specification Revision , Version , This proposal will allow PCIe and SATA to be delivered using a BGA package

can i use gen 4 ssd on gen 3 slot A PCIe x4 SSD card, for example, can be inserted into a PCIe x14 slot, while a PCIe x16 card cannot be inserted into an x1, x2, x4,

can you win money on slot apps 2 drives that only reach 3 GBs at most anyways And in theory, two PCIe lanes can reach GBs throughput, so going down to 2 lanes per 2 SSD that motherboard will map when using Hyper Series Card HYPER GEN 4 CARD supports both PCI Express and PCI Express