[HD2 Android Q&A, Help & Troubleshooting and Genera] Ducter:
I see a lot of confusion on the boards about kernels, files, formats and so on. This is simply a quick and dirty breakdown of some of the words you will see around here, and a hope that it will answer some of the questions I see. If I am mistaken on any of the terms please correct me.

Windows Mobile side of the HD2,

applies to all winmo devices and was answered by RizwanKhan a few years back, and a good explanation of things.

http://xdaforums.com/showpost.php?p=3007244&postcount=2

spl= Secondary Program Loader. Think of this in the same sense as bios on a pc. (it sets where your system boots from, intialises sub system process etc)

sspl = soft spl (this allows you to flash another spl or hardspl).

hardspl = hard spl .. basically it allows flashing of any rom. It protects you from bricking your device. If you have a bad flash it just forces the phone to load into bootloader, from where you can flash another rom using pc or storage card to get your phone working again. Using a hardspl you can flash any carrier rom without cid unlocking your device first.

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radio = controls the transmitting of information from your phone to the tower, including all data inbound and out, different radios seem to work better for Android. .50's generally work well.

task29 = to keep it simple, it basically overwrites your internal memory with 0's or blank data. It ensures that when you go to flash a new ROM nothing is left behind from the old one and gives you a clean slate to work from.

ROM = read only memory, A file which when extracted and flashed holds all the files/folders and information that becomes your OS on your device which will reside on your ROM. You can find them in various forms around here from bare-bones to heavily tweaked and tricked out.

cid = carrier id, a lock basically that prevents you from flashing a ROM to your phone that is not from your official carrier. Fortunately cid locks can be removed easily.

ruu or custom ruu = ROM update utility, basically an exe that extracts the rom or nbh (signed rom) that gives you a nice gui to install/flash by, whether it be a complete ROM or partial.

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Android side of this beast..

kernel = directly from wiki. In computing, the kernel is the central component of most computer operating systems; it is a bridge between applications and the actual data processing done at the hardware level. The kernel's responsibilities include managing the system's resources (the communication between hardware and software components).[1] Usually as a basic component of an operating system, a kernel can provide the lowest-level abstraction layer for the resources (especially processors and I/O devices) that application software must control to perform its function. It typically makes these facilities available to application processes through inter-process communication mechanisms and system calls.

Zimage = A compressed kernel for linux/android. So many different versions that I cant possibly get into them in the scope of this quick breakdown. Basically though remember the newest build offers generally more features but also can be more unstable, more bugs as well. You can easily try a different zimage though so feel free to test them all!!

ROM = currently on the hd2 ROMs are a bit different than regular Android devices as they reside on the sdcard vs NAND, to get a clean ROM you format your sdcard fat32 with a sdcard formatter (hp has a good one) then create a folder called Android on the root of your sdcard, extract your choice Android ROM with 7zip or your choice of compression utility and copy the contents over to the Android folder.

NAND = in short NAND is your phones internal flash memory, hopes are high that with a ROM flashable to NAND our HD'2 will see better battery life, a bit more stable and a bit faster..although it remains to be seen at this point in time.

Modules = basically a driver, some ROMs or Zimages will have broken wifi or similar, you can often replace the driver with a working one that coincides with the Zimage your are using.

ROOT = default account or creation of account that has access to all commands and files, allowing you or an app to modify the file or file system as needed, without having to supply credentials each time.

ADB = Android Debug Bridge is part of the Android SDK, its a command line interface that allows you to modify, remove, replace or create folders/files/apps, basically anything in your phones working system. It is just what it says, a bridge between your device and your computer. Example would be

adb shell mount -o remount rw /system

adb pull system/app/

adb push appname.apk /system/app/

adb shell reboot

that will pull all the apps in your system directory to your computer, the next will push whatever app back to your phone as long as its in the same folder as adb, followed by a reboot. You have tons of commands available, and again, as this is not a detailed guide I wont go into details but wanted to give you a quick idea of what it can be used for. An alternative to ADB is Droid Explorer which offers you a gui to go with it, however I still prefer ADB personally.

APK = basically apps. Much like windows mobile cab files.

At the mention from faisalee, APK files can be installed from the market as well as using various app installers like Linda, App Control and so on. Another good one to have is Titanium Backup which can remove them system apps you may not want (amazon or something), App Monster is another great free app.

As with us on the HD2 currently we may find ourself from one build to the next and Titanium Backup or App Monster can backup all your apps and allow you to reinstall them from a backup folder on your SD. You can also push them over with ADB or use Droid Explorer to do a batch install directly from your pc, all you need is your apps in a folder on your pc and point Droid Explorer to them.

If you find yourself unsure of how to get the apps to your computer and arent to comfortable with ADB, simply grab App Monster or Titanium Backup , back them up then copy the corresponding folder over to your pc.

There are tons of apps that can do what these can, just listing a few to get you started..I am sure you will find your own favorite apps in time.

PPP = Point to Point Protocal, directly from wiki page. In networking, the Point-to-Point Protocol, or PPP, is a data link protocol commonly used in establishing a direct connection between two networking nodes. It can provide connection authentication, transmission encryption privacy, and compression.

PPP is used over many types of physical networks including serial cable, phone line, trunk line, cellular telephone, specialized radio links, and fiber optic links such as SONET. Most Internet service providers (ISPs) use PPP for customer dial-up access to the Internet. Two encapsulated forms of PPP, Point-to-Point Protocol over Ethernet (PPPoE) and Point-to-Point Protocol over ATM (PPPoA), are used by Internet Service Providers (ISPs) to connect Digital Subscriber Line (DSL) Internet service.

PPP is commonly used as a data link layer protocol for connection over synchronous and asynchronous circuits, where it has largely superseded the older, non-standard Serial Line Internet Protocol (SLIP) and telephone company mandated standards (such as Link Access Protocol, Balanced (LAPB) in the X.25 protocol suite). PPP was designed to work with numerous network layer protocols, including Internet Protocol (IP), Novell's Internetwork Packet Exchange (IPX), NBF and AppleTalk.

PPP is also used over broadband connections. RFC 2516 describes Point-to-Point Protocol over Ethernet (PPPoE), a method for transmitting PPP over Ethernet that is sometimes used with DSL. RFC 2364 describes Point-to-Point Protocol over ATM (PPPoA), a method for transmitting PPP over ATM Adaptation Layer 5 (AAL5), which is also sometimes used with DSL.

PPP is specified in RFC 1661.[1]

RMNET = Little is known to me about RMNET, outside of I find it slower on my builds that I have run, some find it more stable but with slower speeds, especially in regards to uploads. A general push is being made now to work with PPP only it seems by most of the Chefs.

APN = Access Point Name, from the wiki again, Access point name (APN) identifies an IP packet data network (PDN), that a mobile data user wants to communicate with. In addition to identifying a PDN, an APN may also be used to define the type of service, (eg connection to wireless application protocol (WAP) server, multimedia messaging service (MMS)), that is provided by the PDN. APN is used in 3GPP data access networks, eg general packet radio service (GPRS), evolved packet core (EPC).

I have read over and over on these boards about "my internets not working" or "I cant MMS" well..its your APN's. If you have a Android build that works for you do yourself a favor and write down the APN's. Or even better yet, go to the market and search for APN Backup and Restore, its a FREE app that does just what it says. Stop asking for XXX Carrier's APN's people, Google is your friend and won't let you down with this search, or like I said, find a build that has working internet and mms and BACK IT UP! Easy enough fix.

AXI = As per michyprima's definition in this thread, AXI scaling downclocks not only the cpu but also the ram to save battery, but can cause lag. use with caution.

FROYO = (frozen yogurt) Google's name for Android 2.2, it has several benefits over 2.1 (eclair) , mainly due to JIT (just-in-time) compiler. Google claims up to 5x faster and if you have used an older build not based on 2.2 you can tell a substantial difference. Several core apps have also seen an update.

Sense vs Stock = Sense is basically HTC's custom UI overlayed on top of stock Android. The differences are some pretty nice looking widgets for social networking, stocks, a people widget and so on. Sense seems to have better luck with Bluetooth and FM radio currently. Your stock HTC running WINMO is running another version of Sense, Androids IMO is a bit nicer. The down side is it is a bit lower then stock but to some its a acceptable trade off. The newer Sense builds are based off the HTC EVO. The EVO has a great deal in common with our HD2 and seems to work well. The stock builds are based off the Nexus One, and work very well as well. They tend to have proper working camera flash and a bit quicker.

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Android is very stable now, if your having issues odds are you did something wrong, your issue has been covered here on these boards I am almost certain, search for your answer and generally you will find what your looking for.

Stop asking what the best Android Build is..these Devs have literally hours upon hours of work in these builds...take a few minutes of your time and try it out, read others comments, if you see a lot of people saying feature XXX or whatever is not working move on to another build.

I know I have left some things out, but my intent was to simply allow new users a quick and dirty way to get caught up on some of the terms they may see around these and many other forums, hopefully cutting down on some of the questions. If a MOD feels this is redundant or should not be posted in the Development section, feel free to remove it or move it to general. My reasoning for posting here was this seems to be where I see most questions asked that this quick guide aims to answer.

If anyone feels I have something incorrect or something needing to be added post away.