Jarring is a process that transfers stored energy in the drill pipe into kinetic energy by releasing a delay mechanism in the jar. This provides a sudden impact. There are two main types of jars: hydraulic jars, which use hydraulic fluid to delay firing, and mechanical jars, which have a preset load to trigger them. Hydraulic jars provide a variable impact depending on applied load and time, while mechanical jars are sensitive only to load. Common jars used in drilling include hydraulic drilling jars, hydraulic/mechanical drilling jars, and power stroke hydraulic drilling jars.