Android 6.0 Marshmallow has been available since October 2015, and at the time of writing is the latest full version of Google's mobile operating system (Nougat is currently in preview). But you might not have it on your phone or tablet.

The reason for this will no doubt be attributable to your wireless carrier or device manufacturer, but if you really want Marshmallow on your device, you can get it by flashing a custom ROM. This means downloading a version of Marshmallow designed for use on your handset and installing it, just as you might switch from Windows to Linux on a desktop PC.

But where do you find a suitable version of Android 6.0 Marshmallow to flash to your phone or tablet? How many are out there, and do they offer a good Marshmallow experience?

Let's find out.

But First: What's Flashing?

If you've come to this article without ever having installed a custom version of Android on your phone or tablet previously, you'll need a bit of an explainer. In short, flashing is the act of writing a new version of Android to your phone. This is typically done using a custom recovery utility, and requires the phone or tablet to be rooted.

Finding a custom ROM suitable for your phone also requires you to know its manufacturer codename, which you can find by googling "manufacturer codename for…" followed by the device name, or simply looking it up on Wikipedia or GSM Arena.

If you've ever installed Ubuntu or Windows from a USB stick, or written a Raspberry Pi OS to an SD card, you'll be able to flash ROMs on your phone. A similar principle lies behind each of these, and it really is quite straightforward once you get used to the recovery software.

CyanogenMod 13 [Broken URL Removed]

Probably the ultimate unofficial ROM, CyanogenMod has been in development since 2008, and by 2012, it had 1 million active users. As many as 50 million devices have run CyanogenMod during their shelf life.

Based on AOSP, CyanogenMod -- also known as CM -- is currently at version 13, and while it won't bring you privacy from the Google element of the Android subsystem, it does offer a quite different Android experience, with custom icons, a custom launcher, native apps and other tweaks.

To find the ROM for your device, scroll down the menu on the right of their website to find the right manufacturer, then click the link for the option that matches your phone or tablet, then Download Latest Release.

Resurrection Remix

One thing you'll notice about Resurrection Remix is that it has an absolutely stunning website. But does the ROM match this presentation? Well, some would argue it's the best ROM out there.

Visually, it's slick, but it owes a lot to the stock Android experience. As you might expect, it is the tweaks that bring something special to Resurrection Remix, such as customizations to the notification drawer, lock screen, quick settings, and many more.

You'll find the download links for Resurrection Remix ROMs at basketbuild.com/devs/resurrectionremix [Broken URL Removed] -- again, tread carefully and look for the manufacturer codename for the device; for instance, the Nexus 5 is known as "Hammerhead," so look for this.

Dirty Unicorns

One of the most popular custom ROMs (perhaps second only to CyanogenMod), Dirty Unicorns has a wide selection of supported devices (including the Google Pixel C), and the most recent Marshmallow release comes with a trio of standout features.

Fling is a customizable gesture-based navigation feature; SmartBar is a customizable overlay for the default navigation bar; and Themes Tile is a tool to change the look of an app based on a pre-selected theme.

To find the right version for your device, head to the Dirty Unicorns link above, click the All Devices drop-down menu, and choose your device name; you'll find the public name listed, along with the manufacturer codename.

OmniROM

Launched by a group of developers disillusioned by CyanogenMod's attraction of venture funding in 2013, OmniROM is perhaps the most private Android ROM option that is available for multiple devices.

We previously described OmniROM as the "spiritual successor" to CyanogenMod, and the choice of Google Apps (gApps) packages available means that you can go for a complete or minimal Google-influenced experience. Having run OmniROM on my Nexus 5 (2013) for six months or so, I can confirm that it is a solid, fast, stable ROM that comes with various tweak packages pre-baked.

The official device list for older versions of OmniROM is long, but Marshmallow is so far limited to a small group of mostly Nexus devices.

crDROID [No Longer Available]

Offering wide device support, crDROID is based on CyanogenMod and squeezes in features from other ROMs, such as OmniROM, SlimROM, and others.

As customizable as you might expect, crDROID embraces those shared features, delivering a rare flexibility. Among the features is the ability to instantly reskin crDROID, which is useful as it potentially removes a key reason to ever flash another ROM. You'll find much more packed into crDROID, though be aware that it has not been updated since 2015.

To flash your copy, head to the download page and click the link that matches your Android handset.

Cataclysm

A collection of impressive new features is available with Cataclysm, from advanced lockscreen options to quick system statistics.

The Smart Radio function automatically alters the radio power mode depending upon the available connectivity, while tweaks are available for the navigation bar, clock style, battery icon, and NFC mode. A bunch of other options are also available, from power menu tweaks to granular app permission management.

Although this ROM is available only for a few Nexus devices, if you own one of the compatible phones, you'll find it is a great experience with a host of tweaks built in. Grab your copy by clicking the link that matches your phone model, then Begin Download.

No ROMs for Your Device? Look Elsewhere!

While the ROMs described here are released across several different models, a lot of work goes into them to ensure compatibility, and as a result, this requires a group of developers to contribute to each project. None is bigger than CyanogenMod, and very little money is involved beside ads clicked on the websites, and donations made in the XDA-Developers forums.

If you have an Android device, and you want to upgrade to Marshmallow before an official update is available, or just want to experience it in a different way, then XDA-Developers.com is the place to go. Here, you'll find a page for your Android device (with very few exceptions), where you should be able to find a Marshmallow ROM that you like the look of. Check the features and screenshots before downloading, and enjoy your new Android experience!

Have you tried any of these Marshmallow custom ROMs? Do you have a favorite that we've overlooked? Tell us about it in the comments.