February 08, 2011, 1:30 PM — If you've sniffed around blogs or articles about mobile phones, you've probably seen mention of "custom ROMs" or "mods." What do they do for a phone? As with rooting, a ton of information is out there; it's far from cohesive, however, and it's spread out all over the Internet. But look no further: We'll walk you through everything you need to know about custom ROMs. Tomorrow, we'll run Part II, which covers kernals, choosing the right ROM, and custom themes.
What Is a Custom ROM/Mod?
Let's start with a quick definition: For the purposes of this article, "custom ROM" and "mod" are interchangeable. Both refer to an already-existing piece of software that a third party has customized, or modified. In this case, you could install a modified version of Android on your phone in place of the stock version of the mobile OS.
Rooting and Custom Recovery
To install and use custom ROMs, you must root your phone (the Android equivalent of iOS jailbreaking) and have Superuser installed on it. For more, see "Rooting Your Android Phone: FAQ," and look for how-tos on your specific model and its current software version, as rooting methods vary greatly from device to device.
You will also need a custom recovery installed and working. A custom recovery is like the launching pad for the phone's OS. It's also where you can make a full backup of the phone (similar to Time Machine in OSX). If something messes up and you can't even get the phone to boot, usually you can still get back to the custom recovery and revert to one of your backups (more on that later). You likely installed a custom recovery when you rooted your phone, especially if you followed a how-to on a site for custom ROMs (such as Cyanogen); make sure that you have one, though, because this is a step you cannot skip.
Your New Best Friend: ROM Manager
Although you can find several ways to install custom ROMs on a phone, ROM Manager is my method of choice. ROM Manager will install Clockwork Recovery (a custom recovery that works quite well). More than that, though, the app has an extremely intuitive interface for downloading and installing ROMs, creating backups or restoring from them, and even installing themes and alternate kernels. It's an easy way to try out a bunch of different mods to see which one works best for your phone.