Very Long Baseline Interferometry (VLBI) is the only space geodetic technic of which observables are sensitive to the whole five Earth orientation parameters, used for coordinate transformation between space‑fixed celestial reference frames where the positions of the celestial bodies are defined and the crust‑fixed terrestrial reference frames where the positions of the geodetic control stations are defined. Hacettepe University VLBI Research Group maintains several tasks like standard analyses of global VLBI sessions, statistical interpretation of the geodetic and astrometric parameters estimated from these analyses and monitoring geodynamic effects which are needed to be reduced from VLBI observations.