The paper presents an analysis of the host properties of 85,224 emission-line galaxies selected from the Sloan Digital Sky Survey (SDSS). The study shows that Seyferts and low-ionization narrow emission-line regions (LINERs) form distinct branches on optical diagnostic diagrams. A new empirical classification scheme is developed to separate star-forming galaxies, composite AGN-H II galaxies, Seyferts, and LINERs. The study finds that LINERs are older, more massive, less dusty, less concentrated, and have higher velocity dispersions and lower [O III] luminosities than Seyfert galaxies. Seyferts and LINERs are most distinguished by their [O III] luminosities. The quantity L[O III]/σ⁴, an indicator of black hole accretion rate relative to the Eddington rate, shows that at fixed L[O III]/σ⁴, differences between Seyfert and LINER host properties disappear. LINERs and Seyferts form a continuous sequence, with LINERs dominant at low L/L_EDD and Seyferts dominant at high L/L_EDD. These results suggest that most LINERs are AGN, and the Seyfert/LINER dichotomy is analogous to the high/low-state models. Pure LINERs require a harder ionizing radiation field with a lower ionization parameter than Seyfert galaxies, consistent with low and high X-ray binary states. The study also compares different classification schemes and finds that previous schemes include starburst-Seyfert composites in the LINER class. The new classification scheme distinguishes between star-forming galaxies, Seyferts, LINERs, and composites. The study finds that LINERs have older stellar populations, higher stellar masses, and lower [O III] luminosities than Seyferts. The stellar velocity dispersion is strongly correlated with optical line ratios for pure LINERs. The [O III] luminosity is higher for Seyferts than for LINERs, with composites having intermediate values. The study concludes that the Seyfert/LINER dichotomy is analogous to the high/low-state models and that pure LINERs require a harder ionizing radiation field with a lower ionization parameter than Seyfert galaxies.The paper presents an analysis of the host properties of 85,224 emission-line galaxies selected from the Sloan Digital Sky Survey (SDSS). The study shows that Seyferts and low-ionization narrow emission-line regions (LINERs) form distinct branches on optical diagnostic diagrams. A new empirical classification scheme is developed to separate star-forming galaxies, composite AGN-H II galaxies, Seyferts, and LINERs. The study finds that LINERs are older, more massive, less dusty, less concentrated, and have higher velocity dispersions and lower [O III] luminosities than Seyfert galaxies. Seyferts and LINERs are most distinguished by their [O III] luminosities. The quantity L[O III]/σ⁴, an indicator of black hole accretion rate relative to the Eddington rate, shows that at fixed L[O III]/σ⁴, differences between Seyfert and LINER host properties disappear. LINERs and Seyferts form a continuous sequence, with LINERs dominant at low L/L_EDD and Seyferts dominant at high L/L_EDD. These results suggest that most LINERs are AGN, and the Seyfert/LINER dichotomy is analogous to the high/low-state models. Pure LINERs require a harder ionizing radiation field with a lower ionization parameter than Seyfert galaxies, consistent with low and high X-ray binary states. The study also compares different classification schemes and finds that previous schemes include starburst-Seyfert composites in the LINER class. The new classification scheme distinguishes between star-forming galaxies, Seyferts, LINERs, and composites. The study finds that LINERs have older stellar populations, higher stellar masses, and lower [O III] luminosities than Seyferts. The stellar velocity dispersion is strongly correlated with optical line ratios for pure LINERs. The [O III] luminosity is higher for Seyferts than for LINERs, with composites having intermediate values. The study concludes that the Seyfert/LINER dichotomy is analogous to the high/low-state models and that pure LINERs require a harder ionizing radiation field with a lower ionization parameter than Seyfert galaxies.