  Very-long-baseline interferometry (VLBI) is a challenging observational
technique, which requires in-depth knowledge about radio telescope
instrumentation, interferometry, and the handling of noisy data. The reduction
of the raw data is mostly left to the scientists and demands the use of complex
algorithms implemented in comprehensive software packages. The correct
application of these algorithms necessitates a good understanding of the
underlying techniques and physics that are at play. The verification of the
processed data produced by the algorithms demands a thorough understanding of
the underlying interferometric VLBI measurements. This review describes the
latest techniques and algorithms that scientists should know about when
analyzing VLBI data.
