Gnuastro is a package of independent programs and a collection of libraries, here we are mainly concerned with the programs. Each program has an official name which consists of one or two words, describing what they do. The latter are printed with no space, for example NoiseChisel or Crop. On the command-line, you can run them with their executable names which start with an ast and might be an abbreviation of the official name, for example astnoisechisel or astcrop, see Executable names.
We will use “ProgramName” for a generic official program name and astprogname for a generic executable name. In this book, the programs are classified based on what they do and thoroughly explained. An alphabetical list of the programs that are installed on your system with this installation are given in Gnuastro programs list. That list also contains the executable names and version numbers along with a one line description.