In galaxy formation models, it is believed that "large" galaxies like the Milkway formed out of the hierarchical merger of smaller galaxies. Detailed studies of small galaxies hence help us understand the galaxy formation and evolution process. In this talk I will discuss studies of nearby, extremely faint dwarf galaxies. These studies are based on observations of the neutral hydrogen hyperfine spectral line using the Giant Metrewave Radio Telescope, at Khodad, near Pune. In particular I will discuss the distribution of dark matter and in these galaxies as well as the processes relevant for conversion of the cold baryonic matter from gas to stars.