  VLBI observations of relativistic outflows (jets) in galactic nuclei,
complemented with detailed studies made in other spectral domains, have become
an effective tool for investigating the physics of nuclear regions in galaxies.
High-resolution radio observations access directly the regions where the jets
are formed, and trace their evolution and interaction with the nuclear
environment. The emission properties, dynamics, and evolution of jets in AGN
are intimately connected to the characteristics of the central supermassive
black hole, accretion disk, and broad-line region (BLR) in active galaxies.
Large VLBI surveys (15GHz VLBA survey, MOJAVE) and dedicated monitoring
programmes follow systematically the evolution of several hundreds of
relativistic jets. These observations, combined with optical and X-ray studies,
yield arguably the most detailed picture of the galactic nuclei. Recent results
from studies of the nuclear regions in several active galaxies with prominent
outflows are reviewed in this contribution.
