  Swift-XRT observations of the X-ray emission from gamma ray bursts (GRBs) and
during the GRB afterglow have led to many new results during the past two
years. One of these exciting results is that approximately 1/3-1/2 of GRBs
contain detectable X-ray flares. The mean fluence of the X-ray flares is ~10
times less than that of the initial prompt emission, but in some cases the
flare is as energetic as the prompt emission itself. The flares display fast
rises and decays, and they sometimes occur at very late times relative to the
prompt emission (sometimes as late as 10^5 s after T_0) with very high peak
fluxes relative to the underlying afterglow decay that has clearly begun prior
to some flares. The temporal and spectral properties of the flares are found to
favor models in which flares arise due to the same GRB internal engine
processes that spawned the prompt GRB emission. Therefore, both long and short
GRB internal engine models must be capable of producing high fluences in the
X-ray band at very late times.
