1. The classical Yang-Mills action. 1.1. Historic remarks. 1.2. The Semisimple Lie Group SU(N) (N [symbol] 2). 1.3. Gauge connection A[symbol] and its field strength F[symbol]. 1.4. Gauge-invariant objects. 1.5. Spontaneous gauge-symmetry breaking. 1.6. Homotopy groups: concept and use -- 2. The perturbative approach at zero temperature. 2.1. General remarks. 2.2. Gauge fixing in the functional integration. 2.3. One-loop running of the gauge coupling -- 3. Aspects of finite-temperature field theory. 3.1. Free-particle partition function: real scalar field. 3.2. Perturbative loop expansion in thermal gauge theory. 3.3. Electric center symmetry -- 4. Selfdual field configurations. 4.1. The BPST instanton and multiinstanton generalization. 4.2. Sketch of the ADHM-Nahm construction. 4.3. SU(2) calorons with k = [symbol]1. 4.4. One-loop quantum weights of clorons -- 5. The deconfining phase. 5.1. Deconfining thermal ground state. 5.2. Free thermal quasiparticles. 5.3. Effective radiative corrections. 5.4. Stable, screened magnetic monopoles. 5.5. Thermomagnetic effect -- 6. The preconfining phase. 6.1. Condensation of magnetic monopole-antimonopole pairs. 6.2. The dual gauge field. 6.3. Abrikosov-Nielsen-Olesen (ANO) vortex lines and center-vortex loops -- 7. The confining phase. 7.1. Decay of the preconfining ground state. 7.2. Nonthermal pressure. 7.3. Evolving center-vortex loops -- 8. The approach of thermal lattice gauge theory. 8.1. Pressure, energy density, and entropy density. 8.2. Differential versus integral method: thermodynamical quantities. 8.3. Analytical aspects of thermal lattice gauge theory -- 9. Black-body anomaly. 9.1. Introduction. 9.2. The Cosmic Microwave Background (CMB). 9.3. SU(2)CMB and thermal photon propagation. 9.4. Determination of Tc. 9.5. Laboratory experiment on black-body anomaly -- 10. Astrophysical and cosmological implications of SU(2)CMB. 10.1. Cold and dilute clouds of atomic hydrogen. 10.2. Large-angle anomalies of the CMB. 10.3. Planck-scale axion and dark energy