The differential is a part of the drive train that is located between the axles. The differential takes power from the engine (via the drive shaft) and turns the axles, thereby delivering power to the wheels. Differentials ensure that the wheels will usually receive equal power even when a vehicle is turning and the inner and outer wheels turn at different rates.
A typical two-wheel drive passenger car has one differential; whereas a four-wheel drive (or all-wheel drive) usually has two differentials; one to work with the front axles, and the other with the rear axles.
Most modern automobiles have limited-slip differentials which ensure that both wheels will receive power even if one of the wheels loses traction. For example, if one wheel passes over ice while the other wheel does not, then the wheel on ice would tend to spin freely, thereby wasting significant amounts of power. But a limited slip differential uses a clutch (or similar) mechanism to ensure both wheels always receive approximately equal amounts of power even if one of the wheels loses traction.
Differentials transmit power through a series of gears which spin very fast and under tremendous pressure. These gears need to be lubricated at all times. Differentials are usually filled with oil. If the seals leak and the oil drains, then the gears will go unlubricated and will wear out or otherwise fail.
In a limited slip differential (your car likely has one), the clutch plates can wear out over time. And the wear-out rate can increase significantly if the differential looses oil or if the oil is old and looses viscosity.
During routine vehicle maintenance you should lensure that a certified mechanic inspects the differential for correct operation and look for signs of wear or other problems like oil leaking or broken seals. The ASE certified mechanics at A&B Transmission and Auto Repair in San Bernardino can perform all routine differential maintenance and repair tasks. They can rebuild your differential if necessary, replacing clutch parts, gears, gear oil, or anything else needed to ensure proper operation of your differential.