Space Division Multiplexing (SDM) in optical fibres is a promising technology to increase data transmission capacity. While traditional methods like wavelength division multiplexing (WDM) have been widely used, SDM offers the potential to significantly enhance capacity by utilizing multiple spatial modes within a fibre. This technology has been underexplored, but recent advancements in fibre technology and coherent detection have made it viable. SDM can be implemented using multicore fibres (MCF) or mode division multiplexing (MDM) in multimode fibres (MMF). MCFs contain multiple cores that can be spaced to minimize crosstalk, while MDM uses different modes within a single fibre to carry independent signals. Both approaches face challenges such as crosstalk and mode coupling, which require sophisticated signal processing techniques like MIMO equalization. Recent experiments have demonstrated high capacity transmission over long distances using SDM, with capacities exceeding 1 Pb/s. The integration of SDM with existing optical networks is also being explored, with efforts to develop components and systems that support SDM. The future of SDM depends on overcoming technical challenges and achieving cost-effective solutions to meet the growing demand for high-capacity optical communication.Space Division Multiplexing (SDM) in optical fibres is a promising technology to increase data transmission capacity. While traditional methods like wavelength division multiplexing (WDM) have been widely used, SDM offers the potential to significantly enhance capacity by utilizing multiple spatial modes within a fibre. This technology has been underexplored, but recent advancements in fibre technology and coherent detection have made it viable. SDM can be implemented using multicore fibres (MCF) or mode division multiplexing (MDM) in multimode fibres (MMF). MCFs contain multiple cores that can be spaced to minimize crosstalk, while MDM uses different modes within a single fibre to carry independent signals. Both approaches face challenges such as crosstalk and mode coupling, which require sophisticated signal processing techniques like MIMO equalization. Recent experiments have demonstrated high capacity transmission over long distances using SDM, with capacities exceeding 1 Pb/s. The integration of SDM with existing optical networks is also being explored, with efforts to develop components and systems that support SDM. The future of SDM depends on overcoming technical challenges and achieving cost-effective solutions to meet the growing demand for high-capacity optical communication.