What is this "r8d" in x64dbg?

Question

I'm debugging my x64 c++ program to learn how it look in x64dbg. I see some register for r8-r15 on the right window, but I don't see r8d. There were others like r15d too. So what is it?

Here is a screenshot of my x64dbg.

Answer 1

The d suffix means its (the 64-bit register's) lower double-word. For example, r8d is accessing r8's lower 32-bit as if it is a 32-bit register.

You can find more info here.