EXCITING is a state-of-the-art full-potential linearized augmented plane wave (FP-LAPW) code which uses quantum mechanics, specifically density functional theory (DFT), to determine the physical properties of solids and molecules. Augmented plane waves provide an almost ideal basis set for computing the Hamiltonian matrix for a periodic solid, and allow for tightly bound core and semi-core electrons to be treated on the same footing as valence electrons.