  The appearance of large, none-Gaussian cumulants of the baryon number
distribution is commonly discussed as a signal for the QCD critical point. We
review the status of the Taylor expansion of cumulant ratios of baryon number
fluctuations along the freeze-out line and also compare QCD results with the
corresponding proton number fluctuations as measured by the STAR Collaboration
at RHIC. To further constrain the location of a possible QCD critical point we
discuss poles of the baryon number fluctuations in the complex plane. Here we
use not only the Taylor coefficients obtained at zero chemical potential but
perform also calculations of Taylor expansion coefficients of the pressure at
purely imaginary chemical potentials.
