What do the dollar ($) and percentage (%) signs represent in x86 assembly?

Question

I am trying to understand how the assembly language works for a micro-computer architecture class, and I keep facing different syntaxes in examples:

sub $48,         


        

Answer 1

This is AT&T syntax for x86. In AT&T % generally denotes a register while $ is reserved for immediates. If you omit th $ the assembler would interpret the 48 as an address.