Supernovae belong to the most powerful explosions in galaxies (only γ-ray bursts seem to be more energetic). They are also the dominant sources of the elements in the Universe, as the Big Bang led only to the formation of H, He, and Li. Heavier elements (in astronomical terms, metals) are to some extent due to stellar winds, which contribute to C, N, O, and some fraction of the heavy elements from Fe to Bi. Supernovae are responsible for all other elements and come in two different kinds, both similar in their output of kinetic energy close to 1051 erg. Type Ia supernovae (SNe Ia) are related to the explosion and complete disruption of a white dwarf in a binary stellar system, which – due to mass transfer from the companion star – exceeds its maximum stable mass (the Chandrasekhar mass, 1.4,M⊙) and contracts. This leads to the ignition of C- and O-burning in an explosive manner, causing a nuclear burning front that disrupts the entire star and ejects about 0.6,M⊙ of Ni/Fe, smaller amounts of intermediate mass elements from Si through Ca, and some unburned C and O into the interstellar medium. As these objects start from very similar initial conditions (a 1.4,M⊙ white dwarf), they emit close to identical light outbursts, which turns them into standard light candles to measure distances in the Universe (this property was the basis for the 2011 Nobel Prize in Physics). While stars with an original mass of less than 8,M⊙ end their stellar evolution as white dwarfs (after having finished H- and He-burning and losing significant amounts of mass in stellar winds), more massive stars pass through advanced nuclear burning stages, also encountering C-, Ne-, O-, and Si-burning and end with a central Fe-core more massive than the Sun. This core consists of matter with the highest binding energy per nucleon and no further nuclear burning can prevent the core collapse up to nuclear densities, causing the formation of a hot so-called protoneutron star. The release of the gained gravitational binding energy of about 1053 erg in the form of neutrinos of all types, plus possibly the winding of magnetic fields due to rotation, permits the ejection of the outer layers with a total kinetic energy of about 1051 erg, similar to SNe Ia. Keywords: nuclear burning; stellar evolution; neutrino wind; core collapse supernovae; explosion mechanism; type Ia supernovae