What is that moaning sound when you apply brakes?

The moaning sound when applying brakes often indicates an issue with the brake system, such as worn brake pads or a lack of lubrication on the brake components. It can also result from vibrations or resonance in the brake parts, especially if the pads are not properly seated. Additionally, moisture or debris between the rotor and pads may cause noise. It's advisable to have a mechanic inspect the brakes to ensure safety and proper function.