### 1.1. What is this FAQ?

**+++UPD**

This FAQ is an attempt to answer common questions on InChI-related concepts and the structure and meaning of InChIs. Where possible we quote directly from the official IUPAC/InChI Trust sites and the distribution. 

The original ‘Unofficial InChI FAQ’ was created by Nick Day at the Unilever Centre, Department of Chemistry, Cambridge University.  In 2011, the document has been revised and updated, with the permission of Nick Day, by the InChI Trust to take into account recent developments of InChI itself and the InChI software; it was then further updated. It has the status of an official FAQ.

The description of InChI in this FAQ corresponds now to the latest software release v. 1.06 of 2019 and to the latest official documentation. Most of the examples below use Standard InChI & InChIKey.