  Very Long Baseline Interferometry, or VLBI, is the observing technique
yielding the highest-resolution images today. Whilst a traditionally large
fraction of VLBI observations is concentrating on Active Galactic Nuclei, the
number of observations concerned with other astronomical objects such as stars
and masers, and with astrometric applications, is significant. In the last
decade, much progress has been made in all of these fields. We give a brief
introduction into the technique of radio interferometry, focussing on the
particularities of VLBI observations, and review recent results which would not
have been possible without VLBI observations.
