A magnetic field is an invisible area around a magnet or a wire carrying electric current in which other magnets or electric currents experience forces. You can imagine a magnetic field as a kind of “invisible cloud of force” that influences the space around the magnet.
Magnetic fields are important in our everyday lives: they ensure that compass needles point in the right direction, electric motors work, and data can be stored on hard drives. The earth itself also has a huge magnetic field that protects us from harmful solar radiation.