  We report the results of a study of the distribution of galaxies in the
projection along the radius ($R \leq 3R_{200c}$) for 157~groups and clusters of
galaxies in the local Universe (0.01 < $z$ < 0.10) with line-of-sight velocity
dispersions~200~km~s$^{-1}$ < $ \sigma$ < 1100~km~s$^{-1}$. We introduce a new
observed boundary for the halos of clusters of galaxies, which we identify with
the splashback radius $R_{\rm{sp}}$. We also identified the core of
groups/clusters of galaxies with the radius$R_c$. These radii are determined by
the observed integrated distribution of the number of galaxies as a function of
squared angular radius from the center of the group/cluster, which (usually)
coincides with the brightest galaxy. We found for the entire sample that the
boundary of dark matter $R_{\rm{sp}}$ for groups/clusters of galaxies is
proportional to the radius $R_{\rm{200c}}$ of the virialized region. We
measured the mean radius $\langle R_{\rm{sp}} \rangle = 1.14\pm0.02$~Mpc for
groups of galaxies ($\sigma \leq 400$~km~s$^{-1}$) and $\langle R_{\rm{sp}}
\rangle = 2.00\pm0.07$~Mpc for clusters of galaxies ($\sigma >
400$~km~s$^{-1}$). The mean ratio of radii is $\langle
R_{\rm{sp}}/R_{\rm{200c}} \rangle = 1.40\pm0.02$}, or $\langle
R_{\rm{sp}}/R_{\rm{200m}} \rangle = 0.88\pm0.02$.
