An overview of the Geant4 low-energy electromagnetic physic package is presented. The package includes detailed simulations of the interactions of particles with energies from about 100 eV to 100 GeV. The emphasis is placed on models in which the accurate description of the atomic structure of media is essential. The package encompasses processes based on different approaches: for electrons and photons one set of implementations is based on the exploitation of evaluated data libraries and allows simulating cross section and energy loss of slow particles, another set is based on analytical models deriving from the Penelope code. For hadrons and ions alternative implementations based on Ziegler and ICRU reviews are provided. Charge-dependent effects are taken into account, and precise models for angular distributions are implemented. Geant4 simulation of some effects important for particle detectors are provided only by the low-energy package: nuclear stopping power, fluorescence of the media due to excitation and ionization of atoms, Auger electron production.