The paper presents a unified view of the spectral energy distributions (SEDs) of blazars, analyzing data from three complete samples: the Slew survey, the 1-Jy BL Lac sample, and the 2-Jy FSRQ sample. The fraction of blazars detected in γ-rays is 17%, 26%, and 40% in these samples, respectively. The γ-ray detected sources do not differ from other sources in terms of redshift, radio and X-ray luminosities, or broad-band spectral indices. The SEDs show a remarkable continuity, with the first peak occurring in different frequency ranges for different samples, and the peak frequency of the γ-ray component correlating with the lower energy one. The luminosity ratio between high and low frequency components increases with bolometric luminosity. This continuity suggests a unified view of the blazar phenomenon, where a single parameter related to luminosity governs the physical properties and radiation mechanisms in both BL Lac and FSRQs. The paper discusses the implications of this unified scheme and presents a detailed theoretical analysis of the SEDs of most γ-ray blazars. The results show that the γ-ray detected sources are representative of the samples as a whole, with no significant differences in terms of radio-to-X-ray broadband properties and power. The synchrotron peak frequency is found to decrease with increasing luminosity, and the broad-band spectral indices are strongly correlated with the synchrotron peak frequency. The γ-ray dominance parameter is also found to correlate with the synchrotron peak frequency. The average SEDs for each sample show a similarity in spectral shape, with the peak frequency of the power emitted between the radio and X-ray band moving from the X-ray to the far infrared band as the samples move from XBL to FSRQ. The results suggest a basic similarity among all blazars irrespective of their original classification and different appearance in a specific spectral band. The paper concludes that the average γ-ray luminosities computed here are necessarily overestimated, but the uncertainties are too large to correct for this effect. The results support the idea of a unified blazar phenomenon, where a single parameter related to luminosity governs the physical properties and radiation mechanisms in both BL Lac and FSRQs.The paper presents a unified view of the spectral energy distributions (SEDs) of blazars, analyzing data from three complete samples: the Slew survey, the 1-Jy BL Lac sample, and the 2-Jy FSRQ sample. The fraction of blazars detected in γ-rays is 17%, 26%, and 40% in these samples, respectively. The γ-ray detected sources do not differ from other sources in terms of redshift, radio and X-ray luminosities, or broad-band spectral indices. The SEDs show a remarkable continuity, with the first peak occurring in different frequency ranges for different samples, and the peak frequency of the γ-ray component correlating with the lower energy one. The luminosity ratio between high and low frequency components increases with bolometric luminosity. This continuity suggests a unified view of the blazar phenomenon, where a single parameter related to luminosity governs the physical properties and radiation mechanisms in both BL Lac and FSRQs. The paper discusses the implications of this unified scheme and presents a detailed theoretical analysis of the SEDs of most γ-ray blazars. The results show that the γ-ray detected sources are representative of the samples as a whole, with no significant differences in terms of radio-to-X-ray broadband properties and power. The synchrotron peak frequency is found to decrease with increasing luminosity, and the broad-band spectral indices are strongly correlated with the synchrotron peak frequency. The γ-ray dominance parameter is also found to correlate with the synchrotron peak frequency. The average SEDs for each sample show a similarity in spectral shape, with the peak frequency of the power emitted between the radio and X-ray band moving from the X-ray to the far infrared band as the samples move from XBL to FSRQ. The results suggest a basic similarity among all blazars irrespective of their original classification and different appearance in a specific spectral band. The paper concludes that the average γ-ray luminosities computed here are necessarily overestimated, but the uncertainties are too large to correct for this effect. The results support the idea of a unified blazar phenomenon, where a single parameter related to luminosity governs the physical properties and radiation mechanisms in both BL Lac and FSRQs.