The pseudo‐spin concept is reviewed: What it is and is not, what it does and does not do, and what it means and does not mean are the issues addressed. Specifically, it is a special basis for carrying out microscopic (fermion) shell‐model calculations in heavy nuclei which exploits the fact that for the single‐particle shell‐model hamiltonian the strength of the spin‐orbit interaction is about four times the strength of the orbit‐orbit term and therefore these two can be transformed into an equivalent pseudo hamiltonian form with a very small spin‐orbit interaction. As a consequence, the pseudo‐LS‐coupled (space‐spin) scheme emerges as the natural choice for a many‐particle shell‐model theory of heavy nuclei. Going beyond the pseudo‐LS coupling scheme to situations where deformation inducing terms dominate the residual two‐body interaction, as is the case for deformed nuclei of the rare earth and actinide regions, the pseudo‐SU(3) scheme and its multi‐ℏ&ohgr; extension, the pseudo‐symplectic model, are shown to be good many‐particle shell‐model theories. A list of applications already completed and some currently underway is given along with results which show that the scheme can be used to reproduce the B(E2:2+ → 0+) strength in238U without the use of an effective charge but that this requires as much as ∼40% vertical (≥2ℏ&ohgr;) mixing.