What does Centos i386 mean?

In linux, we often encounter the i386 i686 istmi586 code, such as viewing the kernel version:

[Root @ localhost logs] # uname-
Linux localhost. localdomain 2.6.18-164. el5PAE #1 SMP Thu Sep 3 04:10:44 EDT 2009 i686 i686 i386 GNU/Linux
You have new mail in/var/spool/mail/root
[Root @ localhost logs] #

Some software may also be downloaded during compilation, such as zend, which we are familiar:

ZendOptimizer-3.2.8-linux-glibc21-i386.tar.gz
ZendOptimizer-3.3.3-linux-glibc23-x86_64.tar.gz

In linux, what does i386 i686 i486 i586 mean?

Actually, it is very simple. I represents intel (intel) series cpu
386 is applicable to almost all x86 platforms, including the old pentum or the new pentum-IV and K7 series CPUs! That I refers to Intel-compatible CPU. As for 386, It is the CPU level!
I586 is a computer of the 586 level. What is it? CPU levels include the first generation of pentum mmx cpu, AMD K5, and K6 series CPU (socket 7 plug-in;
I686 Intel series CPU after pentun II and CPU after K7 all belong to this 686 level!
Noarch is not limited by any hardware level.