The Multiboot specification is an open standard that provides kernels with a uniform way to be booted by Multiboot-compliant bootloaders. The reference implementation of the Multiboot specification is provided by GRUB.| wiki.osdev.org
A bootloader is a program written to load a more complex kernel. Implementation details are gathered in Rolling Your Own Bootloader| wiki.osdev.org
Stack can also refer to the TCP/IP stack in Networking. This article discuss the datastructure and stacks used in architectures. | wiki.osdev.org