- The `IF` statement:
  - The `IF` command is used to compare results.
  - There are three forms of the `IF` command:
    Block
      This is the traditional multi-line `IF` seen in many programming languages.
      This can be combined with `ELSEIF` and `ELSE` clauses.
    One-Line
      This is an `IF` statement with a single action that, as the name implies, is all on a single line.
    Quick Check
      This is a special form of the `IF` statement that can only be used in the shell.
      This form evaluates the expression and prints the value to the terminal.