Source: http://droid-den.com/android-guides/android-rooting-a-glossary-of-terms This is a work in progress, please provide feedback/corrections/additions here or via pm. A2SD This is what we normally call the default Froyo method of storing apps on the sdcard. This is dependent on the application allowing you to store it on the sdcard. You can move apps to the sdcard on froyo by going to settings > Applications > manage applications. Click on an app and then click on move to sdcard. The application will be stored in a folder called .android_secure on your sdcard, in an encrypted state. A2SD+ This is what we normally call the standard rooting method of storing apps onto the sdcard. This essentially tricks the phone into thinking the apps are stored on internal memory (in reality it changes the reference to point to the sdcard, instead of the internal location). The apps are actually stored on an ext partition of the sdcard (you cannot see this on the sdcard yourself) Busybox An application providing a standard set of unix tools. The default toolbox provided by android is limited, so this is required to allow rooted roms/apps to use more advanced unix features. CyanogenMod CyanogenMod is a customized ROM for several Android devices. Their ROMS are typically more stable and have better performance than the stock roms. CyanogenMod also offers a variety features & enhancements that are not currently found in the stock versions of android, such as the ability to easily apply custom themes. Dalvik-cache When your phone starts up, the DalvikVM looks at all your apps and frameworks, and creates a tree of dependencies which is stored in the dalvik-cache. This allows applications to run in an optimised state (and explains why your phone takes longer to boot up after applying a new rom, it's rebuilding the cache.) MCR This is the Modaco Custom ROMS. Modaco is a big name in the rooting community, and he typically releases a stable rooted and customisable version of the stock android roms for phones. Many people use Modaco ROMS because they are extremely similar to the stock roms (for instance they include Sense), but modified to run faster and be more stable, as well as giving the benefit of root and super user access. Nandroid Backup Nandroid Backup is a tool that allows you to fully backup your phones NAND flash memory. In laymens terms, it will create a complete copy of your phone, which you can flash at a later date to come back to the exact state that your phone was in when you created the nandroid backup Radio Firstly, this is not a radio with which you can listen to music or chat shows. The radio you often hear about within rooting is the phones communication radio. All mobile phones have a radio, which allows the phone the ability to transmit and recieve radio waves, such as phone calls. I'm not going to turn this into a technical discussion on how mobile phones work. All you need to know is that you can update the radio firmware on your phone by flashing an updated radio image (via recovery), and that some new ROMs require you to flash a later version of the radio you may already have in order to work correctly. Recovery Recovery mode is a command line interface, available to you before your current ROM is booted up. The recovery mode allows you to do many things such as flashing a new ROM, partitioning your sdcard, wiping the phones data and dalvik cache amongst others things. As such, it is a very powerful tool, but at the same time very dangerous if you don't know what you are doing. The app ROM Manager available in the market gives you a nice interface with which to execute recovery commands from your phone, as well as installing a nice recovery image. Examples of custom recoveries include: Amon Ra Recovery ClockworkMod Recovery Rooting This is the process of applying root to your phone. Basically think of it as unlocking all the options of your phone. By default you are a user, and you have limited privilages to do things on your phone. You cannot really modify any internal aspects of the phone. Rooting gives you a super user access, effectively giving you extra permissions and more freedom to play around with your phone. Things such as taking screenshots, backing up all data to do with an app or overclocking your phones processor.