What Does PCIe x16 Mean? - PC Guide 101
What Does a PCIe Slot Look Like? ... This slot is used for devices like an NVMe M.2 SSD expansion slot or 4K video capture cards that require a higher bandwidth than an x1 slot offer.
NVMe vs. M.2 Drives: Which SSD Is Right for You?
NVMe is the protocol for SSDs, which is faster than the legacy AHCI protocol used in SATA SSDs and hard drives. The form factors for NVMe storage are M.2 and U.2.
Convert M2 slot (used for WIFI module) to SATA ports
I see that the wifi m.0 slot is called M.2 socket 1 but I can't find much about it. It looks like it is commonly used for wifi but can also be used for ethernet, usb.