What is the alternative/similar to the command key?

On a PC keyboard that would be the Windows key, which pressing opens the start menu.

I’m going to assume you are using a Windows keyboard with a Macintosh.

Apple Menu -> System Preferences -> Keyboard -> Modifier Keys (lower right) -> Make it look like this. http://imgur.com/a/KUcHc

Then all your modifier keys will work as normal.

If you are using a mobile device, there isn’t a direct equivalent. You need to research each specific action that you want to do, in order to find ways or alternatives to it.

Was there something specific you want to do?

Thanks everyone. I was thinking about keyboard on a tablet, and there’s for nothing specific, it’s for whennever I come across an instruction.