Nuclear activity in nearby galaxies is a significant phenomenon, with many galaxies showing weak nuclear activity unrelated to normal stellar processes. Recent high-resolution, multiwavelength observations indicate that this activity is primarily due to black hole accretion with a wide range of accretion rates. Low accretion rates in low-luminosity active galactic nuclei (LLAGNs) lead to significant modifications in their central engine, such as the disappearance of the broad-line region and obscuring torus, and the transformation of the optically thick accretion disk into a three-component structure. The local census of nuclear activity supports the notion that most, if not all, bulges host a central supermassive black hole, although some late-type galaxies may host active nuclei without a classical bulge. The paper discusses the spectral classification of galactic nuclei, focusing on the physical motivation, sample spectra, diagnostic diagrams, and starlight subtraction. It covers surveys of nearby galactic nuclei, including the Palomar survey, and discusses host galaxy properties, nuclear properties, excitation mechanisms, and implications for black hole demographics and accretion physics. The study highlights the importance of understanding LLAGNs, which are not simply scaled-down versions of Seyfert galaxies and quasars. The paper also addresses the challenges in detecting black holes in nearby galaxies and the need for alternative constraints on black hole demographics. The study concludes that AGN statistics can provide insights into black hole demographics, including the fraction of galaxies with black holes, their distribution, and environmental influences. The paper emphasizes the importance of studying LLAGNs to understand the poorly understood regime of the central engine governed by low mass accretion rates.Nuclear activity in nearby galaxies is a significant phenomenon, with many galaxies showing weak nuclear activity unrelated to normal stellar processes. Recent high-resolution, multiwavelength observations indicate that this activity is primarily due to black hole accretion with a wide range of accretion rates. Low accretion rates in low-luminosity active galactic nuclei (LLAGNs) lead to significant modifications in their central engine, such as the disappearance of the broad-line region and obscuring torus, and the transformation of the optically thick accretion disk into a three-component structure. The local census of nuclear activity supports the notion that most, if not all, bulges host a central supermassive black hole, although some late-type galaxies may host active nuclei without a classical bulge. The paper discusses the spectral classification of galactic nuclei, focusing on the physical motivation, sample spectra, diagnostic diagrams, and starlight subtraction. It covers surveys of nearby galactic nuclei, including the Palomar survey, and discusses host galaxy properties, nuclear properties, excitation mechanisms, and implications for black hole demographics and accretion physics. The study highlights the importance of understanding LLAGNs, which are not simply scaled-down versions of Seyfert galaxies and quasars. The paper also addresses the challenges in detecting black holes in nearby galaxies and the need for alternative constraints on black hole demographics. The study concludes that AGN statistics can provide insights into black hole demographics, including the fraction of galaxies with black holes, their distribution, and environmental influences. The paper emphasizes the importance of studying LLAGNs to understand the poorly understood regime of the central engine governed by low mass accretion rates.