Why is there 'amd' in the ubuntu iso filename?

If you download iso file with ubuntu you will get something like this:

ubuntu-10.04.3-server-amd64.iso
ubuntu-11.10-desktop-amd64.iso

Every part in the file name is pretty clean to me, except 'amd'. So I have the following questions.

Why is there the 'amd' string in the filename?

What other kind of strings in the filename can be found instead of 'amd'?

It's merely a convention due to the fact that AMD created the 64-bit extensions to the x86 (Intel 386/486/Pentium) instruction set. At that time, Intel was pushing Itanium as the only 64-bit solution, and Intel didn't copy AMD's extensions until it was clear that AMD had created something that was being used widely. The #define AMD64 was used to distingish this 64-bit instruction set from Intel's Itanium instruction set.

AMD beat Intel to adding 64 bit capability to it's X86 line chips, at a time when Intel was pushing the Itanium chip as the future for 64 bit computing in conjunction with HP.

Intel later licensed and implemented the AMD extensions in it's own line of chips.

The amd64 version will work on both AMD's and Intel's current generation chips (other than Itanium, which is largely dead except for some HP servers/workstations). That is if you wish to use 64 bits. It just gives credit to AMD for getting there first.

Sometimes these are referred to as x86_64 as well, which has a slight Intel bias. The x86 name has its roots in the Intel 8086 processor line.