Based on magnetic properties, there are three major types of magnets: permanent, temporary and electromagnets. Permanent magnets retain their magnetism once magnetized while temporary magnets only exhibit magnetic properties whenever they come within range of a magnetic field, and only for a short period. Electromagnets are magnets that only display magnetic properties when current passes through their core.
Permanent magnets can be further divided into four groups based on their composition. Ceramic or ferrite magnet, Samarium Cobalt (SmCo), Neodymium Iron Boron (NIB), and Alnico. Of these four groups, NIB and SmCo are the most powerful. These magnets retain their magnetism for long periods and are rarely affected by temperature changes. Electromagnets are also powerful magnets. However, they become demagnetized once current stops flowing through them. Magnets can also be categorized based on their shape. The most common options include rectangular magnets, disc magnets, donut magnets, round magnets and horseshoe magnets.