Card and Paper
Paper 80-159 gsm - usually works in any printer - ideal for matting and layering.
Card 160-250 gsm - will go through some printers - ideal for matting and layering - heavier weights will stand up if folded into a small-medium card.
Card 250-300 gsm - will go through only a few printers - will fold into a card up to A5 size and stand up.
Card 300-480 gsm - very unlikely to go through a printer - heavier weights are too thick to fold neatly - useful for constructing complex cards and backing other work.
Card 480 gsm+ - extra thick card - usually splits when folded - use for mounting and construction.