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

input/output redirection
I/O redirection

    In Unix, to send ouput from a process
   to different file or device or to another process via a
   pipe, or to have a process read its input from a different
   file, device or pipe.  Some other operating systems have
   similar facilities.

   To redirect input to come from a file instead of the keyboard,
   use "<":

   	myprog < myfile

   Similarly to redirect output to a file instead of the screen:

   	ls > filelist

   A pipe redirects the output of one process directly into the
   input of another

   	who | wc -l

   A common misuse by beginners is

   	cat myfile | myprog

   Which is more or less equivalent to "myprog < myfile" except
   that it introduces an extra unnecessary cat process and buffer
   space for the pipe.  Even the "<" is unnecessary with many
   standard Unix commands since they accept input file names as
   command line arguments anyway.

   Unix's concept of standard input/output and I/O redirection
   make it easy to combine simple processes in powerful ways and
   to use the same commands for different purposes.

   (1998-04-24)