Dmitri Pogosyan CITA Title: Cosmic Structure on Large and Small Scales Analysis of random inhomogeneities is one of main underlying threads in modern theoretical cosmology. Statistical observables of the random fields associated with primary CMB temperature fluctuations, galaxy number density, Sunyaev-Zeldovich fluctuations, weak-lensing shear (to name a few examples of random fields) carry information on the global parameters which define our Universe. The very geometry of tiny density perturbations produced in early Universe explains the morphology of predominately filamentary Web-like pattern of galaxy distribution on large scales. The subject is not restricted to cosmology and large scales. Another example is provided by the fluctuations of radio emission from neutral hydrogen in the disk of our Galaxy. The 21 cm emission carries information about density and velocity distribution of HI and, ultimately, about the nature of the turbulence in the ISM. In my recent work, HI studies have been shown to benefit from statistical techniques similar to the ones used in cosmology. I shall discuss my work in the field, first reviewing the Cosmic Web theory for the Large-Scale Structure but also highlighting my recent results in analyzing HI and CMB data.