The Free On-line Dictionary of Computing (30 December 2018):

Bourne shell

   (sh, Shellish).  The original command-line interpreter
   shell and script language for Unix written by S.R. Bourne
   of Bell Laboratories in 1978.  sh has been superseded for
   interactive use by the Berkeley C shell, csh but still
   widely used for writing shell scripts.

   There were even earlier shells, see glob.  [Details?]

   ash is a Bourne Shell clone.

   ["Unix Time-Sharing System: The Unix Shell", S.R. Bourne,
   Bell Sys Tech J 57(6):1971-1990 (Jul 1978)].