Motherboards feature various expansion slots to accommodate additional components, providing flexibility for system customization and upgrades. PCI (Peripheral Component Interconnect) slots are common and support a range of expansion cards such as sound cards, network adapters, and graphics cards. PCIe (Peripheral Component Interconnect Express) slots have become standard for high-speed connections. PCIe x16 slots are prevalent for graphics cards, offering increased bandwidth for demanding applications. PCIe x1 slots accommodate smaller expansion cards like sound cards or network adapters. M.2 slots, a newer addition, support compact storage devices directly on the motherboard. Additionally, older motherboards may have AGP (Accelerated Graphics Port) slots, primarily used for graphics cards before PCIe became dominant. The variety of expansion slots allows users to customize their systems based on specific performance and functionality requirements.