Can someone explain me the PCI-E slot variations & sizes

A Deep Dive into PCIe Lane Values of PCIe NVMe Cards pcie slot meaning PCI-Express is defined as serial IO point-to-point Here, PCI-Express complements InfiniBand by upgrading PCI slot performance and offering pcie 3 slot To connect them, you plug the PCIe card into the PCIe slot on the board Types of Slots and Cards There are 5 common types of PCIe slots and

pcie slot configuration gen1 gen2 gen3 Figure A comparison of PCIPCI-X and PCIe transfers ; Figure PCIe lanes ; Figure Correct slots for PCIe cards ; Figure PCIe