Help with keyboard shortcut symbols

I'm trying to figure out some keyboard shortcuts for my new MBP, but I'm mystified by the symbols they use. What the heck is a ? , and what's the difference between an arrow that looks like ? and one that looks like ?

I suspect I'm missing something pretty basic, like the proverbial windows user looking for the "any" key.

Edit: Well, it didn't help that the symbols didn't paste properly. I figured out that the first symbol, sortof a backslash with bent ends and a line in the top right corner, is a symbol for the alt/option key. The second symbol, a blocky arrow pointing upwards, is a symbol for the Shift key. I can't figure out the last one, a line arrow pointing to the right, with another perpendicular line stuck on the end of the arrow.

Where can I get a list of keyboard symbols?

Thanks!

The last symbol turned out to be a symbol for Tab. Ironically, the symbol was right there on the keyboard of my old PC laptop that I've been typing on for the past 5 years.