In hydraulics, an air pocket refers to a pocket of air trapped in the hydraulic fluid or system. These pockets can cause problems such as decreased system efficiency, reduced component life, and even complete system failure. This is because air compresses differently than hydraulic fluid, which can result in uneven pressure and cause components to operate erratically. To prevent air pockets from forming, hydraulic systems are typically designed with air bleed valves and other components to remove trapped air.