Interatomic energy transfer phenomena caused by efficient long-range electron correlations are among the most studied processes in atomic physics today. They can provide important insights into the interaction dynamics of single atomic species with their environment in more complex systems. Part I of this book covers fundamental aspects of two interatomic ionization processes relying on the efficient transfer of electronic energy via long-range electron correlations between two spatially well-separated atomic species with an emphasis on the influence of relativistic effects on ionization. Part II of this book deals with an application of interatomic energy transfer in antimatter physics, investigating attachment mechanisms for the production of substantial amounts of the positive ion of antihydrogen in view of experiments on the free-fall of antihydrogen currently planned at CERN.