As Android phones have taken off, rooting (the process of getting super access to your phone, and being able to change it as you see fit) has become an increasingly mainstream thing to do.
The driving factor behind this is the manufacturers: to stamp their own seal on devices, big Android smartphone makers like Samsung, HTC and Sony put a 'skin' on top of the regular Android OS, changing the look and feel, and often replacing stock Android apps with changed varieties.
In the first case, then, some users don't appreciate the 'bloatware' – they'd rather have a clean, unskinned version of Android, as they often run faster, and Google's apps are arguably superior to the manufacturers' offerings.
But skinning Android creates a more serious problem – updates. When Google issues a major update for Android, something it sometimes does a few times a year, it takes months for the manufacturers to apply the updates to their Android skins, and then push the update to customers – and for some older handsets, they often don't bother at all, leaving owners high and dry.
Rooting, and installing custom ROMs, overcomes a lot of that. Not only does messing with the software on your phone allow almost limitless tweaks to the look and feel of the thing, it also brings access to faster, more efficient versions of Android, with more frequent updates to boot.
For a prospective modder, the first step on the path is always rooting. To 'root' a device is to get total control over it. Although most people will never run into problems with having control over their phone, if you ever try to delete an in-built app, you'll find that there's a lot of things the normal operating system won't allow you to change or delete – something rooting changes.
The difficulty of rooting depends on your handset manufacturer. Rooting requires access to the bootloader, a low-level piece of software on your phone that boots up before the operating system, and tells the phone where on its memory to look for the OS.
Some manufacturers unlock the bootloader by default; others offer a tool (not normally exactly user-friendly) on their websites; whilst the worst offenders, by rooting standards, require more complicated (and often warranty-voiding) methods.
From there, rooting normally just requires hooking up your handset to a PC, downloading a few pieces of software, and hitting go. The exact method varies from phone to phone – step-by-step instructions can normally be found on XDA forums, a giant internet community dedicated to developing and modding smartphones.
Getting root access also opens the door to run other, more powerful apps. For example, the most complete backup app, Titanium Backup, needs root to function properly. Other apps, like the power-saving Greenify, also function better when they have complete control; and if you're on a phone plan that charges you extra for tethering your phone's data to your laptop, there are root apps that can get around that too.
However, rooting is just the first, rather limited step. If you want to get a completely un-skinned version of Android, are lusting after the most recent version of Google's OS, or just fancy a change of scenery, you'll want to flash a custom ROM.
A custom ROM is basically just a different version of the Android OS. Generally, the ROM is developed from the open-source Android code, but tweaked slightly.
The modifications vary massively - some just provide you with stock Android, whereas others completely change the look and feel of the phone. Mostly, the ROMs are developed by teams of hobbysists in their spare time, in return for no (or very little) money.
Installing a ROM is just a little more complicated than rooting. You have to install a custom recovery – a piece of software separate from Android, kind of like a very limited alternate operating system.
To start with. you'll need to boot the phone into 'recovery mode', usually achieved by holding some Konami-code-esque combination of buttons as you boot the phone up.
Once in the recovery, you can make system-wide changes like installing ROMs, deleting user data and more. The stock recovery that ships with phones is often very limited, so one of the steps in rooting a phone is normally to install a custom recovery.
There are two particularly common custom recoveries, ClockworkMod and TWRP. Just like the custom ROMs, these are freely available bits of software made by hobbyist hackers, not the actual phone makers, and can be every bit as buggy as you'd expect.
So, once the recovery is installed, all you have to do is find a custom ROM that'll run on your phone, download the file off the internet, copy it onto your phone, then boot into the recovery and flash away ('flashing' basically meaning installing).
Finding a good ROM is probably the most difficult part of the entire operation. One of the most common mistakes for first-time modders is downloading a ROM intended for a slightly different model of smartphone.
Owing to the different mobile networks in various countries, there's normally a couple of versions of any one smartphone in circulation at any one time, which are normally visually identical but sufficiently different on the inside, so that trying to install the wrong bit of software will screw them up.
That said, there is at least a fair bit of choice. There are a number of 'mainstream' custom ROMs, like CyanogenMod, Android Open Kang Project, and the British attempt, MoDaCo. Some focus on upping the processor speed, whilst others offer a vastly different user interface, or better battery life.
If you have a recent, mainstream flagship phone, you'll most likely have all the choice you want; older or less well-known phones don't get the same selection of ROMs, as the demand isn't quite there.
Compounding the problems is the bugginess of many ROMs. Remember, these are bits of software written by enthusiasts in their spare time, and tested by internet forums – not quite the same quality control that big manufacturers go through.
As a result, the latest releases of software can be buggy, and probably aren't recommended to install. At the very least, make sure you read through forum threads to see what problems others are having before installing – problems like the camera or touchscreen stopping working aren't unheard of.
If you do screw your handset up when trying to root or flash a custom ROM, chances are it's easily reversible. Because most features relating to uninstalling or reinstalling Android can be controlled via a PC and a microUSB cable, most problems can be solved by plugging your phone back into your computer, and re-flashing the stock software.
As a general rule, if you can turn your phone on and get into recovery mode, but not the main operating system, it's 'soft bricked'; this is opposed to 'hard bricked', which is when you can't turn the phone on, and it won't talk to a PC. At that point, your options are pretty limited, beyond sending the phone back to the manufacturer and hoping they don't ask too many questions.
Rooting and modding handsets isn't for the faint-hearted – it'll take at least an hour or two to get set up initially, and there's always the outside possibility of bricking your phone – but in many cases, the rewards are worth it.
Whether there's a particular feature that drives you crazy on stock software, or you're tired of waiting half a year for an Android update, most every problem can be solved with a bit of modding. Just don't expect everything to work perfectly, all the time.