In this book, we have identified the benefits of ICTs on economic growth, welfare and competitiveness of productions made by industrial companies. For this purpose, we have evaluated, studied and analyzed the contribution of the digital economy to the sustainable development of developed and underdeveloped countries, especially as digitalization becomes a solution to overcome the Covid pandemic19. We have synthesized the theoretical foundations that have described the effect of the digital economy on sustainable development through wealth creation, service sector change and increased productivity, internal & external trade, competition, job creation, labor productivity and consumer surplus. We have referred to a review of the empirical literature on the impact of the digital economy on socio-economic activities which we have studied the determinants of the use of ICT as well as the impact of these ICTs at the micro-economic scale, at the macro-economic scale and to the energy & tourism as well as, the sustainable development supported.