Tree-level scalar-fermion interactions consistent with the symmetries of the standard model

We present a survey of all possible scalar particles that can couple at the tree level to the standard fermions in the standard model. We discuss the phenomenology of such scalars. In particular, we examine the influence of exotic scalars on $g-2\mathrm{}$ measurements, flavor-changing neutral currents, and $\mathrm{CP}$ violation. We also comment briefly upon decays and production of these particles.