What is the bootloader on my phone or tablet?

Google's Android as an operating system (OS) is loads of fun for persons (like myself) who love tweaking or modifying things.  Running on the right hardware the latest versions of Android (ICS and Jelly Beans) can be tweaked into doing some pretty awesome things, there is just one small problem - you will have to unlock your device's bootloader first.

So what is the bootloader?  And why is it locked in the first place?

Well, the bootloader is the device-specific instructions or software that runs on your device before the operating system loads or kicks in.  To truly understand its purpose you need to understand how your smart device works at its core level.  So here goes:

Similar to how a desktop/laptop computer's hard-drive work, your smart device's storage is divided into several partitions or sections. One partition holds the OS files, another holds the apps you have downloaded and installed along with your documents, pictures etc., and others exists to do more behind-the scenes things.  It is therefore the job of the bootloader to secure these partitions giving you full permission to some while denying access to others in order to protect the system from you interfering with things that could possibly lead to you bricking the device.

A bootloader that is locked does not give you permission to interfere with or change the core or system software that the device comes with.  This means you will not be able to:

1. Change the operating system or flash custom ROMs
2. Remove the bloatware that is bundled with the device
3. Or backup your device  

The device may also have the ability to do much more than it is allowed to do (based on the hardware under the hood), but you won't be able to unleash it true potential unless you're able to unlock the bootloader.

I must hasten to say here that it is in the best interest of the manufacturer of the device to lock the bootloader, that way they will not have to support or cover under warranty devices (phones and tablets) that were hacked to run modified software among other things.  See here.

Unlocking the bootloader of your device is the first step (not the only step) in the direction of freeing your device and getting it to do what YOU want it to do.  Are there risks involved?  YES!  You can end up bricking your device if you do not know what you're doing or if do not follow the instructions and guidelines laid down for unlocking  the bootloader on your device.