Homology modeling (also referred to as template-based modeling (TBM) or comparative modeling) is an important technique that constructs an atomic-resolution model of the target protein on the basis of its amino acid sequence and an experimental three-dimensional structure of a homologous protein. Homology modeling depends on the identification of one or more already known protein structures possibly to resemble the structure of the target sequence, and on the production of an alignment that maps amino acid residues in the target sequence to residues in the template sequence.