These TASI lectures consider low mass hidden sectors from Hidden Valleys,
Quirks and Unparticles. We show how each corresponds to a different limit of
the same class of models: hidden sectors with non-abelian gauge groups with
mass gaps well below a TeV that communicate to the Standard Model through weak
scale suppressed higher dimension operators. We provide concrete examples of
such models and discuss LHC signatures. Lastly we turn to discussing the
application of Hidden Valleys to dark matter sectors.Comment: 35 pages, 21 figure
