Which slot should I use for my SSD?

Note: Most M Key sockets on laptops are backward compatible with SATA bus, but some M Key slots on desktops only support PCI-E bus 2 slot on

NVMe or NVMe+SATA SSD slots are keyed at position “M”, while SATA-only slots are keyed at position “B”

m2 sata slot 2 drives are “keyed” at one end so as to prevent the end-user from inserting them in an incompatible socket PCIe NVMe drives are 'M' keyed SATA ones,

m24 slot wallet What is NVMe M2 SSD and SATA or mSATA