The article, identified as a scientific publication from the ESS Open Archive, delves into the advancements of integrated and efficient 3D electromagnetic (EM) inversion for Controlled-Source Electromagnetic (CSEM) and Magnetotelluric (MT) data. This method represents a significant development in geophysical exploration, aiming to provide a more accurate and higher-resolution understanding of subsurface structures. CSEM and MT are two distinct electromagnetic methods; CSEM typically offers detailed information about shallow resistive targets, such as hydrocarbon reservoirs, while MT provides deeper insights into broader geological structures, including conductive layers. The integration of these two methods through a joint 3D inversion technique is crucial because it leverages their complementary sensitivities, leading to more robust and less ambiguous resistivity models of the Earth's interior. This combined approach addresses limitations inherent in using either method independently, particularly in complex geological environments or when dealing with anisotropic formations where electrical resistivity varies with direction. Numerous studies corroborate the effectiveness of such joint inversion approaches in applications ranging from hydrocarbon detection in marine settings to imaging high-temperature geothermal systems and mineral deposits. The focus on 'efficiency' implies the development of algorithms that can process large datasets more quickly and with fewer computational resources, a persistent challenge in 3D geophysical modeling. This research contributes to reducing uncertainties in subsurface models, which is vital for optimizing resource exploration, environmental monitoring, and geohazard assessment globally.