source command usage

Question

What are the uses of source command in linux. I have created one script and executed using sh test.sh but if I give source test.sh also executing. whats difference?

Linux Help · Answer

"Source - Read  and  execute commands from filename in the current shell environment and return the exit status of the last command executed from filename.  If filename does not contain a slash, file              names in PATH are used to find the directory containing filename.  The file searched for in PATH need not be executable.  When bash is not in posix mode, the current directory  is  searched              if  no  file  is  found  in  PATH.  If the sourcepath option to the shopt builtin command is turned off, the PATH is not searched.  If any arguments are supplied, they become the positional              parameters when filename is executed.  Otherwise the positional parameters are unchanged.  The return status is the status of the last command exited within the script (0 if no commands are              executed), and false if filename is not found or cannot be read.
sh - Bash  is  an  sh-compatible command language interpreter that executes commands read from the standard input or from a file.  Bash also incorporates useful features from the Korn and C shells (ksh       and csh)."