Peripheral Component Interconnect Express (PCIe - PCI-e) Physical Slots

uses the PCIe specification
are expansion slots found on a computer’s motherboard
they allow additional hardware components to be connected to the computer, such as graphics cards, sound cards, network cards, and other peripherals

PCIe Slots - Lanes (×1 ×2 ×4 ×8 ×16 ×32)

A lane is composed of two pairs, with one pair for receiving data and the other for transmitting. Thus, each lane is composed of four wires.

Physical PCIe links may contain 1, 2, 4, 8, 12, 16, or 32 lanes.

consumer CPUs will typically allow for 16 to 24 PCIe lanes
higher-end CPUs will typically allow for 64 or more PCIe lanes

Number of Lanes	Typical Example Cards
x1	Port/Hub Expansions Sound Cards Network Cards Capture Cards
x4	Port/Hub Expansions High-Bandwidth Network Cards NAS Storage RAID Controller Cards Capture Cards M.2 and NVMe Adapters
x8	Higher-Bandwidth Implementations of other Expansion Cards Multi-Slot NVMe Adapters Low-End Graphics Cards that are actually made for PCIe x8 slot lengths (something like an AMD RX 560)
x16	Graphics Cards, in general Enthusiast or Server-Grade Expansion Cards (Network and Storage most common)

PCIe Slots - Chipset Lanes vs Processor Lanes

Chipset Lane	connects directly to chipset limited bandwidth bottlenecked by chipset generally connect to USB, other M.2 and PCIe slots, and SATA
Processor Lane	connects directly to processor more bandwidth not bottlenecked by chipset generally connect to GPU and M.2 slots