AMD invented 64-bit extensions back when Microsoft was busy trying to differentiate between their "big metal" Itanium chips and consumer processors. Turns out everyone wanted more memory and didn't want to have to rewrite all of their apps to get it.

Intel then had to license it, but because it's Intel they refused to call it AMD64. So the industry as a whole just started saying x86-64 to mean both AMD64 and Intel 64 so that the general consumer wouldn't think that insert app wasn't compatible with both.

It's actually the x86-64 instruction set, that is to say, the 64-bit version of x86. AMD created the first implementation of this set with AMD64, and Intel then adopted it with their own flavor as Intel 64. I don't think the headline is as accurate as it could be. Probably wrote the headline with the assumption that "most readers" would better understand "64-bit Intel" than "x86-64" but they might be underestimating their readers! And even then, it's officially called "Intel 64" according to Wikipedia.

https://en.wikipedia.org/wiki/X86-64#Intel_64

> x86-64 (also known as x64, x86_64, AMD64 and Intel 64)

One official name among others. Linux distros tend to refer to it as amd64.