The simplified molecular input line entry specification or SMILES is a line notation for the chemical structure of molecules. It uses a short series ASCII characters to represent structures. Most molecule editor computer programs can draw a two-dimensional diagram or a three-dimensional model of a molecule based on its SMILES code.
Arthur Weininger and David Weininger wrote the original SMILES specification in the late 1980s. It has since been modified and extended by others, including by Daylight Chemical Information Systems Inc. In 2007, the Blue Obelisk open-source chemistry community developed an open standard called "OpenSMILES".
In July 2006, the IUPAC introduced the InChI as a standard line notation for representing chemical structures. People think that it is easier for humans to understand SMILES than InChI. Some chemists argue that SMILES is better than InChI because many different software programs support it. SMILES also has theoretical (for example, graph theory) backing.