The hyphen - before the command vports

I used "VPORTS" command in auto cad 13. It poped up a dialogue. While"-vports"command it popped up the promp text. It has different function.

Is there basic rules about hyphen before a command or without hyphen.

Because for each command whatever I type in ,there is '''-' before the command line showed.

Am I stupid to ask this question?

By the way , cad13 don't have vports button activated in the tool bar(view- vports), that is why I have to type in VPORTS command to make a v-port

Some commands have additional options or work differently when invoked from the command prompt. Another example would be the Purge command.

No, you are not stupid for asking about the use of a hyphen before a command.

The hyphen is used to invoke a command line only version of many commands so they can be used by scripts, macros, keyboard users, etc. that cannot use a dialog box.

Another example is "layer" and "-layer"

I prefer typing over clicking, so I tend to use hyphenated options as much as possible.