A boot loader is a small program that loads an operating system into a computer’s memory during the startup process. It is the first software that runs when a computer is powered on, initializing the system and handing control over to the operating system kernel. The boot loader is typically stored in the system’s Master Boot Record (MBR) or GUID Partition Table (GPT). Common boot loaders in Linux include GRUB (GNU GRand Unified Bootloader) and LILO (Linux Loader). The boot loader allows users to select from multiple operating systems or kernel configurations if they are installed, facilitating multi-boot setups and providing recovery options if needed.