The GOODS–Herschel key program presents the deepest far-infrared (FIR) observations of galaxies at 0 < z < 2.5 using the Herschel Space Observatory. The study examines the infrared (IR) spectral energy distributions (SEDs) of these galaxies and compares them with a local reference sample from IRAS, ISO, Spitzer, and AKARI data. The total IR luminosity (L_IR) of local galaxies is determined from their radio and mid-IR continuum sizes. The ratio of total IR luminosity to rest-frame 8 μm luminosity (IR8 ≡ L_IR / L_8) follows a Gaussian distribution centered at IR8 = 4 (σ = 1.6), defining an IR main sequence for star-forming galaxies independent of redshift and luminosity. Outliers from this main sequence, with higher IR8 values, are shown to consist of starbursts with compact star formation densities. IR8 can separate galaxies with normal and extended star formation modes from compact starbursts. The rest-frame UV-2700 Å size of distant starbursts is typically half that of main sequence galaxies, supporting the correlation between star formation density and starburst activity. Luminous and ultraluminous IR galaxies (U)LIRGs are systematically in the starburst mode, whereas most distant (U)LIRGs form stars in the "normal" main sequence mode. This confusion between two star formation modes is the cause of the "mid-IR excess" population of galaxies found at z > 1.5. Main sequence galaxies have strong PAH emission features, a broad far-IR bump, and an effective T_dust ≈ 31 K. Starburst galaxies exhibit weak PAH features and a sharper far-IR bump with T_dust ≈ 40 K. The study shows that the mid-to-far IR emission of X-ray active galactic nuclei (AGN) is predominantly produced by star formation, and that candidate dusty AGNs with a power-law emission in the mid-IR systematically occur in compact, dusty starbursts. After correcting for the effect of starbursts on IR8, new candidates for extremely obscured AGNs are identified. The IR main sequence is directly related to the redshift-dependent SFR – M* relation and can separate galaxies between normal star formation and starbursts. The study uses the IR8 bolometric correction factor to address the "mid-IR excess" problem and shows that IR8 correlates with IR surface brightness and starburst intensity. The universality of IR8 among main sequence star-forming galaxies is used to produce a prototypical IR SED. The study combines Spitzer and Herschel photometry to derive composite SEDs for main sequence and starburst galaxies. Galaxies with AGN signatures are discussed, and a technique to identify obscured AGN candidates is presented. The study usesThe GOODS–Herschel key program presents the deepest far-infrared (FIR) observations of galaxies at 0 < z < 2.5 using the Herschel Space Observatory. The study examines the infrared (IR) spectral energy distributions (SEDs) of these galaxies and compares them with a local reference sample from IRAS, ISO, Spitzer, and AKARI data. The total IR luminosity (L_IR) of local galaxies is determined from their radio and mid-IR continuum sizes. The ratio of total IR luminosity to rest-frame 8 μm luminosity (IR8 ≡ L_IR / L_8) follows a Gaussian distribution centered at IR8 = 4 (σ = 1.6), defining an IR main sequence for star-forming galaxies independent of redshift and luminosity. Outliers from this main sequence, with higher IR8 values, are shown to consist of starbursts with compact star formation densities. IR8 can separate galaxies with normal and extended star formation modes from compact starbursts. The rest-frame UV-2700 Å size of distant starbursts is typically half that of main sequence galaxies, supporting the correlation between star formation density and starburst activity. Luminous and ultraluminous IR galaxies (U)LIRGs are systematically in the starburst mode, whereas most distant (U)LIRGs form stars in the "normal" main sequence mode. This confusion between two star formation modes is the cause of the "mid-IR excess" population of galaxies found at z > 1.5. Main sequence galaxies have strong PAH emission features, a broad far-IR bump, and an effective T_dust ≈ 31 K. Starburst galaxies exhibit weak PAH features and a sharper far-IR bump with T_dust ≈ 40 K. The study shows that the mid-to-far IR emission of X-ray active galactic nuclei (AGN) is predominantly produced by star formation, and that candidate dusty AGNs with a power-law emission in the mid-IR systematically occur in compact, dusty starbursts. After correcting for the effect of starbursts on IR8, new candidates for extremely obscured AGNs are identified. The IR main sequence is directly related to the redshift-dependent SFR – M* relation and can separate galaxies between normal star formation and starbursts. The study uses the IR8 bolometric correction factor to address the "mid-IR excess" problem and shows that IR8 correlates with IR surface brightness and starburst intensity. The universality of IR8 among main sequence star-forming galaxies is used to produce a prototypical IR SED. The study combines Spitzer and Herschel photometry to derive composite SEDs for main sequence and starburst galaxies. Galaxies with AGN signatures are discussed, and a technique to identify obscured AGN candidates is presented. The study uses