PXELINUX is a lightweight bootloader that allows computers to boot over a network using the Preboot Execution Environment (PXE) protocol. It is part of the SYSLINUX project and is commonly used in environments where multiple systems need to be booted from a central server, such as in data centers or for network installations. By using PXELINUX, administrators can easily manage and deploy operating systems without needing physical media like USB drives or CDs. This tool supports various file systems and can load different types of operating systems, making it versatile for various network booting scenarios.