Ferrite is a ceramic material that has magnetic properties and is used in many types of electronic devices. It is made by mixing and firing iron(III) oxide with one or more additional metallic elements, such as strontium, barium, manganese, nickel, and zinc). Ferrites are ferrimagnetic, meaning they are attracted by magnetic fields and can be magnetized to become permanent magnets). Unlike other ferromagnetic materials, most ferrites are not electrically conductive, making them useful in applications like magnetic cores for transformers to suppress eddy currents). Ferrites can be divided into two families based on their resistance to being demagnetized (magnetic coercivity) ).

Ferrites are hard, brittle, and polycrystalline, meaning they are made up of a large number of small crystals. They are generally gray or black in color and composed of iron oxide and one or more other metals in chemical combination. Ferrites are used in permanent magnets, ferrite cores for transformers and toroidal inductors, computer memory elements, and solid-state devices. Ferrite beads, which are passive electronic components that can suppress high frequency signals on a power supply line, are also made of ferrite.

Ferrite cores are made of metal oxide ceramics containing a mixture of iron oxide and oxides of magnesium-zinc or nickel-zinc. They are effective at slowing down the rapid rising of electrostatic discharge current spikes or voltage surges in cables. A cylinder made of ferrite is the most commonly used ferrite core for cable noise or EMI suppression. With the material and shape selection, the characteristics of a ferrite core can be completely altered. The parameter that changes with the material and shape is ferrite impedance. At high frequencies, the quality factor of ferrite cores is low and offers minimum issues associated with resonance.