Editing Bootloader (section)

==Second-stage boot loader==
{{Anchor|SECOND-STAGE}}
Second-stage boot loaders, such as [[GNU GRUB]], [[rEFInd]], [[Windows Boot Manager|BOOTMGR]], [[Syslinux]], and [[NTLDR]], are not themselves operating systems, but are able to load an operating system properly and transfer execution to it; the operating system subsequently initializes itself and may load extra [[device driver]]s.

Second-stage implementations can include interactive user interfaces, allowing boot option selection and parameter modification. They handle kernel loading, including processing of [[Initial ramdisk|initrd/initramfs]] images, and can pass boot parameters to the [[Kernel (operating system)|kernel]]. Many implement modular designs supporting loadable modules for additional functionality. These choices can include different operating systems (for [[Multi-booting|dual or multi-booting]] from different partitions or drives), different versions of the same operating system (in case a new version has unexpected problems), different operating system loading options (e.g., booting into a rescue or [[safe mode]]), and some standalone programs that can function without an operating system, such as memory testers (e.g., [[Memtest86|memtest86+]]), a basic shell (as in GNU GRUB), or even games (see [[List of PC booter games]]).<ref>{{cite web|url=http://www.coreboot.org/Tint|title=Tint |publisher=coreboot|access-date=20 November 2010}}</ref> Some boot loaders can also load other boot loaders; for example, GRUB loads BOOTMGR instead of loading Windows directly. Usually, a default choice is preselected with a time delay during which a user can press a key to change the choice; after this delay, the default choice is automatically run so normal booting can occur without interaction.
They may also handle compression, cryptographic verification, and chain-loading of other bootloaders.
The boot process can be considered complete when the computer is ready to interact with the user, or the operating system is capable of running system programs or application programs.