In general, Magnets are the objects that produce a type of energy which are called as magnetic fields. Usually, all the magnets possess a property called polarity which means, a magnet's power of attraction is strongest at its opposite ends which is usually called the north and south poles.
The north and south poles usually attract each other, but North Pole repels north and South Pole repels south. Generally, all magnets attract iron.Permanent MagnetsThe most commonly used types of magnets are the permanent magnets. Once magnetized, Permanent magnets are those types of magnets which can retain their magnetism. They are used as hooks, compass, audio speakers, jewelry making.
The permanent magnets are further divided into different types of magnets based on their composition like:Temporary MagnetsThese types of magnets act like permanent magnets only when they are within a range of a strong magnetic field and are known as temporary magnets. They lose their magnetism, As soon as these magnets are removed from the field. The objects that act as temporary types of magnets are paperclips, iron nails, etc. telephones, electric motors, even in the production of electricity, make use of the temporary types of magnets.
ElectromagnetsMagnets that are a tightly wound coil of wire and when current flows through the coil of wire, usually with an iron core, it acts like a permanent magnet is known as electromagnets. Polarity and strength of the magnetic field of the electromagnets can be easily changed. By changing the flow of current direction and by changing the magnitude of the current flowing through the wire, change of polarity can be done. Large cranes, lifting cables and rods during construction, television, computers, radios, video tapes, speakers, etc make use of these types of magnets.
SuperconductorsThe strongest types of magnets are the superconductors. Without a metal core, these magnets are also made of wire coils of special metal alloys. When they are cooled at very low temperatures, these metal alloys become superconductors. In Magnetic Resonance Imaging (MRI) machines, NMR equipments, mass spectrometers, magnetic separation process and particle accelerators, etc, the superconductor types of magnets.