Variables behave as placeholders, but data is typed.
You do not have to declare variables, because they are automatically created when you use them. No longer used memory, i.e. memory-frames where no variable points to, are automatically freed by the garbage collector. Ruby is free, also for commercial applications many existing libraries make programming easy Ruby is permanently developed, without loosing backward-compatibility There are interfaces to Python, Perl and Java. Thus existing programs can be reused.