An area below the circles and around the net where players usually drive hard or move the puck to create scoring chances. It also can be referenced to when teams cycle the puck in the corners.
Some of the best power forwards in the game have dominated this area of the ice and score by using their strength or determination. Phil Esposito, John LeClair and Joe Thornton were known for their down-low domination.
Many teams will also set up their powerplays to move the puck "down low" once the defense is out of position or so they can open up a passing lane to the point for one-time shots.
Another area where "down low" can be used is when teams cycle the puck around in the corners to get the defense moving in hopes of, at some point, getting an open lane to find someone in a good shooting position in front of the net. Henrik Sedin and Daniel Sedin are known for their cycling and "down low" play that leads to many goals.