Android Poweruser: What is the Bootloader? | Pocketnow. This is a short, sweet and accurate description of bootloaders. Specifically, that software added to phone operating systems by the handset manufacturer to control what software you load on your device. It controls what Operating System, and what version of it, that you can load. Even though Linux (Android) is open source, phone manufacturers add their own flavor to Android, and their own software, and they want to be sure you use it. Since most Android users want complete control over their handsets, there are hackers out there who help users unlock the bootloader. This is an important step, along with rooting, that permits the user to install other versions of Android on their phone. Enlightened manufacturers are selling phones with unlocked bootloaders, or making it easy to unlock. Now, if you get into a conversation with a power user, you will be able to converse intelligently.