Guide to icons?

I don’t speak icon.

When I’m told “go to the XXXXX icon” I’m often confused. What does the XXXX icon look like?

“Well, it’s a kinda squiggly thingie, sort of a circle with a fish swimming in it, smoking a cigar, sort of.”

For a serious example, yesterday I tried to scan a form on my printer and was told to find the scan icon. None of the icons I saw screamed out “scan” to me. is there a universal “scan” icon I’m unaware of?

More generally, is there a guide to icons so I could just look these up in the future?

Icon symbology is pretty inconsistent, although there are a few widely agreed ones. I wouldn’t get my hopes up that an icon for an obscure operation or a specific application would conform to any guide. Especially if the developer is of the “screw standards, ain’t nobody got time for standards” mindset.

Curiously, this list doesn’t include a “scan” icon, other than a QR code, but this page might help:

A “scan” icon will typically just look like the top of a scanner or copier, like this:
https://maxcdn.icons8.com/Share/icon/ios7/Computer_Hardware/scanner1600.png
Or, it may be more abstract, like this: