  We review the dispersion-theoretical analysis of the electromagnetic form
factors of the nucleon. We emphasize in particular the role of unitarity and
analyticity in the construction of the isoscalar and isovector spectral
functions. We present new results on the extraction of the nucleon radii, the
electric and magnetic form factors and the extraction of $\omega$-meson
couplings. All this is supplemented by a detailed calculation of the
theoretical uncertainties, using bootstrap and Bayesian methods to pin down the
statistical errors, while systematic errors are determined from variations of
the spectral functions. We also discuss the physics of the time-like form
factors and point out further issues to be addressed in this framework.
