Scattering amplitudes in quantum field theory Introduction and Foundations On shell Techniques for Tree level Amplitudes Loop Integrands and Amplitudes Loop Integration Techniques and Special Functions Solutions to the Exercises. . This open access book bridges a gap between introductory Quantum Field Theory (QFT) courses and state of the art research in scattering amplitudes. It covers the path from basic definitions of QFT to amplitudes which are relevant for processes in the Standard Model of particle physics. The book begins with a concise yet self contained introduction to QFT including perturbative quantum gravity. It then presents modern methods for calculating scattering amplitudes focusing on tree level amplitudes loop level integrands and loop integration techniques. These methods help to reveal intriguing relations between gauge and gravity amplitudes and are of increasing importance for obtaining high precision predictions for collider experiments such as those at the Large Hadron Collider as well as for foundational mathematical physics studies in QFT including recent applications to gravitational wave physics.These course tested lecture notes include numerous exercises with solutions. Requiring only minimal knowledge of QFT they are well suited for MSc and PhD students as a preparation for research projects in theoretical particle physics. They can be used as a one semester graduate level course or as a self study guide for researchers interested in fundamental aspects of quantum field theory.