In the U.S. and Canada, paper weight is specified using an arcane system based on 500 sheets of a basis size (or "basic size") of a named category of paper: bond, text, cover, etc. Business supply stores will use the bond weight (most common: 20lb, occasionally 24, 28, 32 are also available). Professional printers will more commonly use the text (also called offset) weight to talk about the same paper.

table of the most common equivalent weights

(conversions are approximate, especially GSM (metric g/m²); not all equivalents are commonly manufactured; actual GSM varies between manufacturers)

Bond	Text	Cover	GSM
20	50	-	75 gsm
24	60	-	90 gsm
28	70	-	106 gsm
32	80	45	119 gsm
40	100	56	151 gsm
47	120	65	177 gsm

In my experience (in Canada) 80, 100, and 130 lb. cover are also common, but you wouldn't see it sold under text or bond weights.

(i graduated 2 months ago, i thought i was free of this ordeal)