This book presents various many-body techniques used to describe nuclei from the basic interactions among nucleons. It provides a brief description of modern nuclear forces and their application in finite nuclei. It also includes an overview of several many-body techniques used in the field, including quantum Monte Carlo, configuration interaction, and coupled cluster methods. The book covers the key algorithms necessary to build out and/or use computer codes for simple problems. It also focuses on important high-performance computing aspects, modern computing languages, parallelization methods and libraries, and basic quantum many-body training.