To further elaborate on FBinNN reply. Not all square taper crank and bottom bracket (BB) combinations are compatible. Although nearly all spindles use a 2 degree taper (to match a 2 degree taper in the crankarm), there are two competing standards, defined by the measurement across the flat at the end of the spindle. The JIS size is used by Shimano and most other Asian manufacturers. The ISO size is primarily used by Campagnolo and other European manufacturers.

So yes, make sure your BB is compatible with your crankset.