Quantum Chromodynamics (QCD) continues to be an active field of research, which one can see from the number of publications in the field, as well as from the number of presentations at different QCD dedicated conferences, such as the regular QCD-Montpellier Conference Series. This continuous activity is due to the relative difficulty in tackling its non-perturbative aspects, although its asymptotic freedom property has facilated perturbative calculations of different hard and jet processes. Therefore, we think it is still useful to write a book on QCD in which, besides the usual pedagogical introduction to the field, some reviews of its modern developments, which have not yet been ‘compiled’ into a book, will be presented. Elementary introductions at the level of pre-Ph.D. in different specialized topics of QCD will be discussed, which may be useful for a future deeper research and for a guide in a given subject.

We start the book with a general elementary introduction to strong interactions, parton and quark models, …, and present the basic tools for understanding QCD as a gauge field theory (renormalization, operator product expansion, …). After, we present the usual hard processes (deep inelastic scattering, jets, …) calculable in perturbative QCD, and discuss the resummation (renormalons, …) of the perturbative series. Later, we discuss the different modern non-perturbative aspects of QCD (lattice, effective theories, …).