White dwarf stars represent the most common endpoint of stellar evolution. In fact, about 90% of all stars will end up as white dwarfs. Their high temperatures and low luminosities imply that they are small — only about the size of the Earth (R e = 0.009R⊙). The mean radius for white dwarfs is R = 0.01 R⊙ (see the first table). Their rather ordinary masses of M ≈ 0.6M⊙ indicate that they have been gravitationally compressed to enormously high densities of about 100,000 g cm-3. Degenerate electron pressure stabilizes these stars against further collapse.