M.2 is a physical form factor (a socket shape and size standard) found on motherboards that allows you to connect solid-state drives (SSDs) and other components without traditional cables.
The slot looks like a narrow rectangular notch and accepts a small, flat module about the size of a stick of chewing gum. M.2 drives sit perpendicular to the motherboard and click in at an angle, then lie flat when fully inserted. This design saves space compared to older 2.5-inch SSD enclosures or 3.5-inch hard drives.
Two different protocols run through M.2 slots. SATA M.2 drives use the same slower technology as traditional hard drives, whilst NVMe (Non-Volatile Memory Express) drives use the faster PCIe connection. Most modern M.2 slots support NVMe, which offers much faster read and write speeds (often 3,500 to 7,000 MB/s depending on the PCIe version). A single M.2 slot can only use one protocol at a time.
Real-world example: A gaming PC with an M.2 NVMe SSD boots Windows in seconds and loads large game files almost instantly, compared to the minutes a traditional hard drive would take.
When buying a PC or motherboard, check how many M.2 slots it has and whether they support NVMe. Verify the PCIe generation (PCIe 4.0 or 5.0 are current standards) to match the speed of the drive you plan to use. Most modern budget and mid-range systems include at least one M.2 NVMe slot, making it the standard for new builds.