The off stump is the stump on the batter’s off side, away from the legs. Bowlers target it to tempt batters into risky shots. For example, a delivery outside off stump can draw a batter into a drive and induce an edge to the slip fielders. Batters align their stance and bat angle considering the off stump.
Pro-Tip: Watching the line of the off stump helps batters judge which balls are safe to leave.