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.

So let’s talk about what a bootloader is, and why Verizon wants to lock yours down. What is a bootloader? The bootloader is the first thing that starts up when a phone is turned on.

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

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

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

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 ...

There's been a lot of chatter going around the interwebs in the past 24 hours about the Droid X's exceptionally well-locked bootloader -- a situation that is going to make running custom ROMs ...

The most obvious consequence of living with an unlocked bootloader Android device is that some financial apps, among others, will outright refuse to run out of security concerns.