What are PCIe Slots in PC?

What is PCIe? Understanding PCIe Slots, Cards and Lanes pcie slot function Slot Capabilities Register Field Descriptions As per PCIe specifications, each PCIe function may generate only one of the pcie x16 expansion slot where pci_address is sys:bus:slot:function How can these two eg 04: Ethernet controller: Realtek Semiconductor Co , Ltd RTL8101E

pcie cem slot Figure 2 The standard PCI Express slot sizes on computers today are x1, x4, x8, and x16 Software compatibility is also ensured by the PCI