A spiral galaxyhas a rotating stellar/gas disk with spiral structure, central bulge, extended halo and globular clusters, embedded in a still larger dark-matter distribution. For the Milky Wayuseful rough scales are a stellar-disk diameter of a few tens of kiloparsecs, athin-disk thickness of a few hundred parsecs, a bulge scale of kiloparsecs and a halo extending tens to hundreds of kiloparsecs depending on tracer. Young stars follow gas-richstar-forming disk regions and spiral arms. Very old stars are prominent in globular clusters, halo and bulge, though the disk also contains old populations. These are distributions with overlapping ages, not disjoint bins.