ABINIT is an open-source first-principles software implementing a diverse range of formalisms such as DFT, density-functional perturbation theory (DFPT), many-body perturbation theory (GW approximation and Bethe-Salpeter equation), and dynamical mean-field theory among others. Since it relies on plane waves to represent the wavefunctions, periodic boundary conditions are imposed. ABINIT is thus particularly suited to deal with periodic structures, although this limitation can be circumvented by embedding non-periodic systems in the appropriate supercell. Both norm-conserving pseudopotentials and the projectoraugmented wave method are supported. Numerous quantities can be calculated including electronic, vibrational, optical, magnetic, mechanical, and thermodynamic properties.