  The four major approximation schemes devised to study the modification of
jets in dense matter are outlined. The comparisons are restricted to basic
assumptions and approximations made in each case and the calculation
methodology used. Emergent underlying similarities between apparently disparate
methods brought about by the approximation schemes are exposed.
Parameterizations of the medium in each scheme are discussed in terms of the
transport coefficient $\hat{q}$. Discrepancies between the estimates obtained
from the four schemes are discussed. Recent developments in the basic theory
and phenomenology of energy loss are highlighted.
