A type of line notation introduced by IUPAC. The acronym stands for International Chemical Identifier. Originally, it was IChI (IUPAC chemical identifier). An InChI can give a large amount of chemical information displayed in layers and sublayers separated by forward slashes. For example, the InChI for naphthalene is
Here, InChI=1 indicates the version of InChI used. The remainder of the string is the main layer. It consists of three sublayers. These are (1) the molecular formula (C10H8), (2) the atom-connection information (starting with c), and (3) the hydrogens present (starting with h).
Other layers can be added for such information as charge, stereochemistry, and isotopic composition.
https://www.inchi-trust.org/technical-faq-2/#1.1 An FAQ produced by the InChI Trust
https://iupac.org/who-we-are/divisions/division-details/inchi/ Information and downloads from the IUPAC site