  The decade-old formulation of the isolated horizon classically and within
loop quantum gravity, and the extraction of the microcanonical entropy of such
a horizon from this formulation, is reviewed, in view of recent renewed
interest. There are two main approaches to this problem: one employs an SU(2)
Chern-Simons theory describing the isolated horizon degrees of freedom, while
the other uses a reduced U(1) Chern-Simons theory obtained from the SU(2)
theory, with appropriate constraints imposed on the spectrum of boundary states
`living' on the horizon. It is shown that both these ways lead to the same
infinite series asymptotic in horizon area for the microcanonical entropy of an
isolated horizon. The leading area term is followed by an unambiguous
correction term logarithmic in area with a coefficient $-\frac32$, with
subleading corrections dropping off as inverse powers of the area.
