The surface temperature of the sun is about 5,800 kelvins. The temperature at the core of the sun is at least 15,000,000 kelvins. Most of the sun's constituent particles at the surface are gaseous atoms, as no liquid or solid can exist at such high temperatures.
The extremely high temperature of the core is what makes it possible for the nuclei of atoms to collide and produce nuclear fusion reactions. These reactions generate the sun's energy which feeds life on Earth. The extremely high temperatures that are required to sustain fusion reactions occur only in about 10 percent of the sun.