Metal-organic frameworks (MOFs) are one of the fastest-growing classes of materials prepared by the self-assembly of metal ions or clusters with organic ligands. Different from other porous solids such as zeolites, silica, or activated carbon, MOFs are unique due to their high porosity, low density, and high structural tunability. By changing the metal site and/or the organic ligand, different structures with a variety of properties can be achieved. MOFs have been employed for a wide variety of applications in areas such as gas capture and separation, catalysis, sensing, textile upgrading, humidity control, drug delivery, among others.