Why unable to invest in Gold, etc

Hi

New to all this… a basic question…

Why are yuo able to view Gold, Silver, and some funds like usa tech 100, but NOT actually able to invest?

Are they different types of financial instruments? are they investable elsewhere?

Thanks!

Thanks for that, now i see how i can invest in gold… i was looking at AXUUSD… how about usa tech 100… can i invest in that some other way?

Thank you! appreciated