Magnetic fields in the Sun and Sun-like stars are generated by a dynamo, a process involving the rotation of the star as well as convection, the rising and falling of hot gas in the star's interior.
Understanding the magnetic dynamo of our Sun is important because it is responsible for a lot of interesting and energetic solar phenomena, some of which can have a considerable impact on our Earth and the wider Solar System.
The Sun's magnetic field is responsible for sunspots on its surface, the 22-year magnetic activity cycle (the "Solar cycle"), the Solar wind that pummels planets throughout our Solar System and the ejections of large quantities of plasma – a gas composed of free electrons and free atomic nuclei – known as coronal mass ejections.
This ejected material can have a serious impact on Earth, resulting in geomagnetic storms that disrupt radio transmissions, damage satellites and electrical grids, as well as harm astronauts or even people flying in airplanes at high altitudes.