A masterly survey of the last 13 years of Very Long Baseline
Interferometry, reviewed in light of the most advanced astronomical
observations. Topics covered include: Nonthermal emission from
extragalactic radio sources; Principles of synchrotron emission in
relation to astrophysics; Theory of relativistic jets; Young, powerful
radio sources and their evolution; Scintillation in extragalactic radio
sources; Radio and optical interferometry; Radio polarimetry; Unified
schemes; Deep fields; Tropospheric and ionospheric phase calibration;
Supernovae; VLBI for geodesy and geodynamics.