When the brake pedal is applied the brake calipers are compressed against the brake rotor (aka brake disc) The brake pads convert the kinetic energy of the car to thermal energy by friction of the pads against the rotor. When a brake pads are heated from being pressured against the drum or rotor, it transfers small amounts of friction material to the brake rotor or brake pad. The brake rotor / disk (both of which will now each contain amounts of friction material which in turn will cause the rotor / disc to and the pad to "adhere" to each other and provide the stopping power to stop the vehicle. The friction of the pad against the rotor / disk is however responsible for the majority of stopping power. In disc brake applications, there are usually two brake pads per disc rotor, held together by a brake caliper which are usually attached to a wheel hub or suspension upright.
Brake pads are manufactured in various hard and soft compounds for numerous applications depending on their intended use. The softer compounds are used in racing applications and more aggressive braking applications, while the harder compounds are used more for durability, but less aggressive stopping power. Extreme care should always be taken when installing pads or fitting non standard brake pads, as operating temperature ranges may vary, such as performance pads not braking efficiently when cold or standard pads fading under hard driving. Harder pads such as metallic and ceramic compounds tend to give off less dust but can be very hard in wearing down the brake rotors. The softer organic pads do not wear down the rotor as fast as the the harder compounds, but tend to give off that dreaded black dust that accumulates on the wheels.
There are many manufacturers of OEM brand brake pads such as Pagid, Textar and Jurid for European vehicles such as Audi, BMW, Mercedes, Porsche, Volvo, Volkswagen and more. Akebono and Nippon are OEM brake pad manufacturers for many Asian vehicles such as Honda, Mazda, Toyota, Lexus and more. For performance and metallic compound pads there are Mintex brake pads, PBR Metal Master brake pads, PBR Organic brake pads and also PBR Ceramic brake pads. Akebono also manufacturers OEM Act and Pro Act ceramic pads for European and OEM Asian vehicle applications. Pex for brake pad sensors.