简要来说，启动引导程序是电脑开机后运行的第一个软件。

Briefly, a boot loader is the first software program that runs when a computer starts.

youdao

GRUB启动引导程序仅搜寻特定的启动分区，找到后加载第二阶段的启动引导程序。

The GRUB MBR boot loader merely searches for a special boot partition and loads a second stage boot loader.

youdao

如果这个磁盘是可启动的，那么第一个扇区被称为启动扇区，因为这是启动引导代码存在的地方。

If the disk is bootable, the first sector is called the boot sector, since this is where the boot loader code resides.

youdao