So, I'm pretty bad with PC's and I'm looking to buy a new PC from FiercePC. I'm looking through the list of things I can improve to make the PC better and I see M.2 SSD. I have no clue what this is so I am wondering if this is required for a PC to work, like Windows 10, or a graphics card? Or is it just something that you can have to make it better but not needed?