  Data on high energy nuclear collisions collected at the Relativistic Heavy
Ion Collider over the past decade have provided convincing evidence that
hadronization is quite different in hot nuclear environments compared to p+p
collisions. In particular, the data suggest that we see traces of quark degrees
of freedom in elliptic flow, with the implication that collective flow is
generated on the parton level and is transfered to hadrons through a simple
recombination step. In this contribution we review the experimental evidence
for quark recombination and discuss some recombination models which are used to
describe these effects.
