MOV src, dest (or) MOV dest, src?

Question

MOV is probably the first instruction everyone learns while learning ASM.

Just now I encountered a book Assembly Language Programming in GNU/Linux for IA32 Architect

Answer 1

mov dest, src is called Intel syntax. (e.g. mov eax, 123)

mov src, dest is called AT&T syntax. (e.g. mov $123, %eax)

UNIX assemblers including the GNU assembler uses AT&T syntax, all other x86 assemblers I know of uses Intel syntax. You can read up on the differences on wikipedia.