Q:

What does Grave accent (`) symbol do in terminal

When I type Grave accent(`) symbol in terminal, It is like down below.
>
>
>

What does Grave accent(`) symbol do?

A:

The '>' is displayed because the shell 'waits' for the closing quote.
From the man page:
Command Substitution
       Command substitution allows the output of a command to replace the com-
       mand name.  There are two forms:
          $(command)
   or
          `command`

   Bash performs the expansion by executing command and replacing the com-
   mand substitution with the standard output of  the  command,  with  any
   trailing newlines deleted.  Embedded newlines are not deleted, but they
   may be removed during word splitting.  The command  substitution  $(cat
   file) can be replaced by the equivalent but faster $(< file).

