Today’s cosmology requires precision and accuracy of distance measurements more than ever. The tip of the red giant branch (TRGB) is an ideal standard candle for the cosmology of the nearby universe. The TRGB will be more popular in the coming age with future telescopes. Some interesting science cases in the TRGB cosmology will be presented: 1) the Hubble tension, 2) Virgo infall and dark matter, 3) almost dark galaxies, and 4) dark matter-free galaxies.