  I review the various mechanisms for creating bars in rotating stellar disks,
and conclude that the swing-amplified feed-back loop, which produces rapidly
tumbling bars, remains the most probable. The bar continues to evolve after its
formation in a number of ways; here I discuss what appears to be inevitable
thickening normal to the plane, continued spiral activity in the outer disk and
also underscore the increasingly important problem presented by angular
momentum loss to the halo. Finally, I examine possible means, excluding
interaction, by which bars in galaxies could be destroyed.
