919 Screening Sand, sometimes called Paver Sand, is used as base material underneath the pavers. Some installers will also use a 1/2" of Diamond Sand on top of the Screening Sand for properly leveling of the pavers.
Screening sand can either be brought by 1-ton bags or in bulk, where it is delivered with your pavers on pallets, or a dump truck that will dump the sand. For small amounts of sand, 300 SF or less, it makes much more sense to buy sand by the bag.
Generally, if you are installing pavers over a sand base, you'll need approximately one ton of sand for every 100 SF. This can vary by job and location. For jobs that are 125 SF to 250 SF, two bags should be enough.