This article reviews recent advancements in photodetectors based on two-dimensional (2D) materials and heterostructures, focusing on their design and performance. The review highlights the importance of both the active elements and device architecture in photodetection, emphasizing the role of charge carrier generation, separation, and extraction. The article discusses various 2D materials, including transition metal dichalcogenides (TMDCs), hexagonal boron nitride (h-BN), and black phosphorus (BP), and their heterostructures. It covers the photodetection properties of these materials across different spectral ranges, including ultraviolet (UV), visible (Vis), near-infrared (NIR), short-wave infrared (SWIR), mid-wave infrared (MWIR), long-wave infrared (LWIR), and terahertz (THz) ranges. The review also examines the effects of the pyro-phototronic effect (PPE), localized surface plasmon resonance (LSPR), and photothermoelectric effect (PTE) on photodetector performance. It discusses various photodetector mechanisms, such as the photoconductive effect, photogating effect, photovoltaic effect, and bolometric effect, and their applications in different photodetection scenarios. The article also addresses the challenges in photodetector performance and proposes solutions to enhance their figures of merit. The review concludes with an overview of the current state of 2D-based photodetectors and their potential for future applications in various fields.This article reviews recent advancements in photodetectors based on two-dimensional (2D) materials and heterostructures, focusing on their design and performance. The review highlights the importance of both the active elements and device architecture in photodetection, emphasizing the role of charge carrier generation, separation, and extraction. The article discusses various 2D materials, including transition metal dichalcogenides (TMDCs), hexagonal boron nitride (h-BN), and black phosphorus (BP), and their heterostructures. It covers the photodetection properties of these materials across different spectral ranges, including ultraviolet (UV), visible (Vis), near-infrared (NIR), short-wave infrared (SWIR), mid-wave infrared (MWIR), long-wave infrared (LWIR), and terahertz (THz) ranges. The review also examines the effects of the pyro-phototronic effect (PPE), localized surface plasmon resonance (LSPR), and photothermoelectric effect (PTE) on photodetector performance. It discusses various photodetector mechanisms, such as the photoconductive effect, photogating effect, photovoltaic effect, and bolometric effect, and their applications in different photodetection scenarios. The article also addresses the challenges in photodetector performance and proposes solutions to enhance their figures of merit. The review concludes with an overview of the current state of 2D-based photodetectors and their potential for future applications in various fields.