First off, the bootloader isn't part of Android, it's what lets the device boot into Android. Device manufacturers generally want you to stick to the version of Android they preloaded on the device.

The picture above was taken by Alexei Watson who states that the new stock recovery in Android L has a few new features. You can now Reboot to Bootloader, and Power down.

If you want to unlock your phone’s bootloader, then you’re in great luck–we have a step-by-step guide on how to unlock the Galaxy Nexus’ bootloader.

adb reboot bootloader 8. Your tablet will turn off and reboot to the bootloader. 9. Type the following command: fastboot oem unlock *This step will fully wipe your device, just like a factory ...

For reference, I have an OG Pixel. Bootloader is unlocked, but everything else is stock Android after flashing the March image just this morning.

The Asus Transformer Prime will be getting Ice Cream Sandwich on 12 January, with an unlocked bootloader en route.

Google: carriers should give Android users freedom to unlock bootloader An Android security engineer challenges the need for device lockdown and says … ...

Sony Ericsson recently added a new section to their developer world portal called Unlocking the boot loader. They provide all the information and tools needed to root some of their newer Android ...

Despite the risks you take, an unlocked bootloader is the first step in being able to fully customize your Nexus 10. This guide shows you how to unlock or relock the Nexus 10 bootloader.