Our modern understanding of galaxy evolution relies heavily on the exchange of matter between galaxies and the intergalactic medium (IGM) to explain a broad range of observable galaxy properties (color bimodality, mass-metallicity relationship, etc.). The competition between mass gain and loss plays out in the circumgalactic medium (CGM). QSO absorption lines can be selected to probe the CGM, and in a small pilot study of these absorbers we have disovered that our view of the metal content in the Universe at z<1 may have been biased toward the high end metallicity. We have discovered a population of very metal-poor absorbers (<2% solar) at z<1, >15 times smaller than the mean metallicity at these redshifts. These provide the best-yet observational evidence for cold accretion flows like those present in numerical simulations of galaxies. At the same time, we clearly see the signature of galaxy outflows in these absorbers. We propose a COS Legacy archival program to characterize the metallicity and physics of the diffuse matter around galaxies. We will use the high resolution z<1.5 QSO spectra in the HST/COS G130M/G160M archive to address the questions: What is the metallicity of the extended galaxy halos at z<1? What are the baryon and metal budgets of CGM gas at z<1? We will produce a public database of the 200 coadded QSO spectra with a line identification list for each QSO, which will provide the definitive database for studying the low-redshift IGM and the IGM-galaxy connection and undoubtedly leads to several major ancillary discoveries. QUASAR ABSORPTION LINES AND IGM 12 Legacy false false 0.0 0.0 false false false SUPPORTED