The 4x4 pattern is the most common insert setup on snowboards, featuring four bolt holes arranged in a 4cm x 4cm grid on each side of the board. If you ride a board from brands like Ride, Salomon, Jones, Lib Tech, or Gnu, you almost certainly have a 4x4 pattern.
This system is considered the universal standard because nearly every binding on the market includes a 4x4-compatible disc right out of the box. It lets you adjust your stance width and binding angles in 1cm increments, which is plenty of precision for most riders.
The main thing to watch for is if you have a Burton board—those use either the Channel system or the older 3D pattern instead. But if your board isn't a Burton, 4x4 is almost guaranteed to be what you're working with, making binding shopping straightforward.