When a programmer writes the subroutine statement in a program, then subroutine can modify its arguments, but it does not return a value.

BY Best Interview Question ON 03 Mar 2019

Example

subroutine name(arg1, arg2, ....)
    [declarations, including those for the arguments]
    [executable statements]
end subroutine [name]

A subroutine is invokes using the call statement.