ChemApp
-------

ChemApp is a **software library** that contains code that can be run by calling
it from an application that you create. Since it is a library, ChemApp cannot
be run by itself. You need to create an application (write a program) to call
its functions.

The ChemApp library contains a set of 75 functions, all of which have a name
that starts with the letters ``tq``. We refer to this set of functions as
ChemApp's **basic API**. An :term:`API` is a set of components like functions
that programmers can use to call the library when they develop applications. As
you use ChemApp for Python to write programs to do thermochemical calculations,
you can therefore use ChemApp's basic :term:`API`, or one of the other APIs
provided within ChemApp for Python.

GTT-Technologies released three different **editions of ChemApp**, namely
Development, Redistributable, and Light. The **Development** edition is intended
for people developing new applications with ChemApp, and the **Redistributable**
edition for packaging and distributing applications that were developed with the
Developer edition. The **Light** edition is provided free of charge for
demonstration purposes, but has limited functionality. ChemApp for Python is
intended to be a development tool, and is only provided in Development and Light
editions.