Hydrodynamics can be defined as the effective description of how many-particle systems evolve from local equilibrium to global equilibrium. This talk gives several examples of how electrons show different kinds of hydrodynamical behavior compared to an ordinary fluid. One-dimensional systems often show special behavior because of additional exact or approximate conservation laws, which can be verified by comparison to DMRG-type simulations. As an example, we show how examining neutron scattering data on a model Heisenberg chain compound in a previously neglected regime of moderate temperature and small wave vector shows the superdiffusive z=3/2 behavior characteristic of the Kardar-Parisi-Zhang universality class. Higher-dimensional electron systems also show unique features, for example because they move in an environment of low symmetry, and we close by discussing how Hall viscosity and related conductivity properties are seen or might be seen in experiments.