  Loop-tree duality allows to express virtual contributions in terms of
phase-space integrals, thus leading to a direct comparison with real radiation
terms. In this talk, we review the basis of the method and describe its
application to regularize Feynman integrals. Performing an integrand-level
combination of real and virtual terms, we obtain finite contributions that can
be computed in four-dimensions. Moreover, this method provides a natural
physical interpretation of infrared singularities, their origin and the way
that they cancel in the complete computation.
