The make command can be invoked with no arguments, simply:
demo% make
The make utility looks for a file named makefile or Makefile in the current directory and takes its instructions from that file.
The make utility:
Reads makefile to determine all the target files it must process, the files they depend on, and the commands needed to build them.
Finds the date and time each file was last changed.
Rebuilds any target file that is older than any of the files it depends on, using the commands from makefile for that target.