  This review presents experimental results on the inter-edge-state transport
in the quantum Hall effect, mostly obtained in the regime of high imbalance.
The application of a special geometry makes it possible to perform I-V
spectroscopy between individual edge channels in both the integer and the
fractional regime. This makes it possible to study in detail a number of
physical effects such as the creation of topological defects in the integer
quantum Hall effect and neutral collective modes excitation in fractional
regime. The while many of the experimental findings are well explained within
established theories of the quantum Hall effects, a number of observations give
new insight into the local structure at the sample edge, which can serve as a
starting point for further theoretical studies.
