  In contrast with common non-relativistic lore, the usual Sachs form factors
are not the Fourier transforms of charge or magnetization densities. Instead,
the two-dimensional Fourier transform of the electromagnetic $F_1$ form factor
is the charge charge density of partons in the transverse plane. An analysis of
the available data for neutron form factors leads to the result that the
neutron charge density is negative at the center, and that the square of the
transverse charge radius is positive. This contrasts with many expectations.
Additionally, the use of measured proton form factors leads to the result that
the proton's central $u$ quark charge density is larger than that of the $d$
quark by about 80%. The proton (neutron) charge density has a long range
positively (negatively) charged component indicative of a pion cloud.
