This review presents the basic ideas and techniques of spectral density functional theory used in electronic structure calculations of strongly-correlated materials, where the one-electron description breaks down. The method is illustrated with examples where interactions play a dominant role, such as systems near metal-insulator transitions, volume collapse transitions, and systems with local moments. The review discusses the development of dynamical mean-field theory (DMFT), which maps the full many-body problem onto a quantum impurity model. DMFT provides a minimal description of the electronic structure of correlated materials, treating both Hubbard bands and quasiparticle bands on the same footing. It becomes exact in the limit of infinite lattice coordination. Recent advances have combined DMFT with electronic structure techniques, offering the possibility of turning DMFT into a useful method for computer-aided material design involving strongly correlated materials. The review introduces the rapidly developing field of electronic structure calculations of strongly-correlated materials, presenting concepts and computational tools that allow a first-principles description of these systems. It reviews the work of both the many-body physics and electronic structure communities, highlighting the importance of DMFT in accessing new regimes for which traditional methods based on extensions of DFT do not work. The review discusses the effective action formalism and the constraining field, which allows for a unified description of many approaches to electronic structure. It also covers density functional theory, the Baym-Kadanoff functional, and the formulation in terms of the screened interaction. The review concludes with an assessment of the approaches, emphasizing the importance of DMFT in understanding the behavior of strongly-correlated materials.This review presents the basic ideas and techniques of spectral density functional theory used in electronic structure calculations of strongly-correlated materials, where the one-electron description breaks down. The method is illustrated with examples where interactions play a dominant role, such as systems near metal-insulator transitions, volume collapse transitions, and systems with local moments. The review discusses the development of dynamical mean-field theory (DMFT), which maps the full many-body problem onto a quantum impurity model. DMFT provides a minimal description of the electronic structure of correlated materials, treating both Hubbard bands and quasiparticle bands on the same footing. It becomes exact in the limit of infinite lattice coordination. Recent advances have combined DMFT with electronic structure techniques, offering the possibility of turning DMFT into a useful method for computer-aided material design involving strongly correlated materials. The review introduces the rapidly developing field of electronic structure calculations of strongly-correlated materials, presenting concepts and computational tools that allow a first-principles description of these systems. It reviews the work of both the many-body physics and electronic structure communities, highlighting the importance of DMFT in accessing new regimes for which traditional methods based on extensions of DFT do not work. The review discusses the effective action formalism and the constraining field, which allows for a unified description of many approaches to electronic structure. It also covers density functional theory, the Baym-Kadanoff functional, and the formulation in terms of the screened interaction. The review concludes with an assessment of the approaches, emphasizing the importance of DMFT in understanding the behavior of strongly-correlated materials.