In Irons
If the boat attempts to tack with a slow initial speed, or otherwise loses forward motion while heading into the wind, the boat will coast to a stop and the lack of water flow over the rudder will cause the sailor to lose the ability to steer the boat. Stopped head-to-wind, a sailboat is said to be "in irons". To recover from being in irons, one or more sails can be "backed" by sheeting or pushing them to one side. A sail backed to one side near the bow of the boat will tend to push the bow to the other side, and the boat may "pay off" in that direction so that the sails can be trimmed again and normal sailing resumed. A sail backed further aft may make a boat begin to "sternboard" or make way backwards. If this is possible the rudder can be used to steer the boat out of the no-go zone.
Read more about this topic: Points Of Sail