  We build a simple analytical model for the bias of dark matter halos that
applies to objects defined by an arbitrary density threshold,
$200\leq\deltas\leq 1600$, and that provides accurate predictions from low-mass
to high-mass halos. We point out that it is possible to build simple and
efficient models, with no free parameter for the halo bias, by using integral
constraints that govern the behavior of low-mass and typical halos, whereas the
properties of rare massive halos are derived through explicit asymptotic
approaches. We also describe how to take into account the impact of halo
motions on their bias, using their linear displacement field. We obtain a good
agreement with numerical simulations for the halo mass functions and
large-scale bias at redshifts $0\leq z \leq 2.5$, for halos defined by a
nonlinear density threshold $200\leq\deltas\leq 1600$. We also evaluate the
impact on the halo bias of two common approximations, i) neglecting halo
motions, and ii) linearizing the halo two-point correlation.
