What is PCIe? Understanding PCIe Slots, Cards and Lanes

Can someone explain me the PCI-E slot variations & sizes of pcie slot meaning Every PC, including commercial and industrial computing solutions, comes equipped with at least one PCIe slot, with some computers having pcie 2 slot almost all CPUs have x16 lanes going directly into the GPU pcie slot on the motherboard imagine data travels like cars in these lanes you can

pciex16 slot configuration A PCIe card will fit into a slot of its size or bigger, but not into a smaller PCIe slot x or later standard, meaning that, a PCI-X card can be installed