Linux Magazine: Linux and the AMD64

“Linux was created on the first 32-bit CPU in the x86 CPU
family, the 80386. Since then, computing has evolved substantially,
and while 32-bit computing remains adequate for many purposes, its
days are nearing an end. Increasing demand for RAM will soon
dictate a shift to 64-bit architectures.

“Fortunately, 64-bit CPUs are currently available and are
beginning to move into the mainstream. One of these architectures,
AMD’s AMD64, is gaining in popularity, and seems likely to dominate
the market currently held by its Intel Architecture-32 (IA-32, or
x86) predecessor…”