  This dissertation examines the phenomenology of statistical hadronization at
ultrarelativistic energies. We start with an overview of current experimental
and theoretical issues in Relativistic heavy ion physics. We then introduce
statistical hadronization, and show how it gives a description of particle
abundances and spectra through covariance and entropy maximization. We argue
that a distinction can be made between equilibrated staged freeze-out in which
post-formation hadron interactions play an important role in determining
final-state observables, and non-equilibrium sudden freeze-out where spectra
and abundances get determined at the same time and further interactions are
negligible. We attempt to falsify sudden freeze-out by examining whether
particle abundances and spectra can be described using the same formation
temperature. This is done both in the equilibrium framework, and using a
chemical non-equilibrium ansatz. Our fits to experimental data suggest that the
sudden freeze-out model explains both the particle abundances and spectra. We
then try to extract the particle formation temperature, and quantify
post-freeze-out hadronic interactions using experimentally observable
resonances. We discuss observed resonances and suggest further measurements
that have the potential to distinguish between the possible freeze-out
scenarios experimentally. Finally, we infer from experimental data how particle
formation proceeds in spacetime, in particular whether freeze-out dynamics
agrees with the sudden freeze-out expectation. We examine particle spectra, and
show that they are not sensitive enough to pick the right freeze-out dynamics.
We suggest resonances and azimuthal anisotropy as experimental probes for this
task.
