OS X: Keyboard shortcuts – Apple Support.
I admit it! Although I’ve been using Macs as long as there have been Macs, I still can’t remember those weird symbols that represent the Macintosh “modifier” keys. Okay, the “clover leaf”, i.e. Command key, is easy, but do you really recognize all the other ones? Can you distinguish an Option key from a Caps Lock?
In any case, I present them here from Apple’s most excellent “OS X: Keyboard shortcuts page”. Go there. I guarantee you will learn something. Or use the page to jump to another good one, like how to access the special character variations: