  The usual approach to classify the ionizing source using optical spectroscopy
is based on the use of diagnostic diagrams that compares the relative strength
of pairs of collisitional metallic lines (e.g., [O iii] and [N ii]) with
respect to recombination hydrogen lines (e.g., H{\beta} and H{\alpha}). Despite
of being accepted as the standard procedure, it present known problems,
including confusion regimes and/or limitations related to the required
signal-to-noise of the involved emission lines. These problems affect not only
our intrinsic understanding of inter-stellar medium and its poroperties, but
also fundamental galaxy properties, such as the star-formation rate and the
oxygen abundance, and key questions just as the fraction of active galactic
nuclei, among several others. We explore the existing alternatives in the
literature to minimize the confusion among different ionizing sources and
proposed a new simple diagram that uses the equivalent width and the velocity
dispersion from one single emission line, H{\alpha}, to classify the ionizing
sources. We use aperture limited and spatial resolved spectroscopic data in the
nearby Universe (z{\sim}0.01) to demonstrate that the new diagram, that we
called WHaD, segregates the different ionizing sources in a more efficient way
that previously adopted procedures. A new set of regions are defined in this
diagram to select betweeen different ionizing sources. The new proposed diagram
is well placed to determine the ionizing source when only H{\alpha} is
available, or when the signal-to-noise of the emission lines involved in the
classical diagnostic diagrams (e.g., H{\beta}).
