[**Homebrew**](https://en.wikipedia.org/wiki/List_of_homebrew_video_games) usually be referrin' to software that be not authorized by Nintendo. It allows ye to run homebrew games, tools fer save editin' 'n backin' up, 'n emulators fer various older systems.
In many cases, runnin' homebrew on ye device be 100% free usin' jus' th' Nintendo 3DS Sound app. There also be various other exploits in commercial games 'n th' browser fer gettin' homebrew runnin'.
**Custom Firmware** ("CFW") enables ye to use more advanced hacks that userland homebrew can't easily do. Fer instance, signature patches let ye be installin' unsigned titles that appear right on ye HOME Menu.
boot9strap be th' newest 'n best method 'o launchin' Custom Firmware that gives us nearly full control 'o th' system only milliseconds into boot, which be similar to th' effect 'o BootMii fer th' Wii. It be givin' us even earlier control than arm9loaderhax did, 'n unlike standard sighax, boot9strap uses an NDMA overwrite exploit in order to be gainin' Boot9 code execution. 'Tis be meanin' that any console runnin' boot9strap be capable 'o dumpin' th' console unique OTP (`OTP.bin`), th' ARM11 bootrom (`boot11.bin`), 'n th' ARM9 bootrom (`boot9.bin`).
The benefits of boot9strap over other Custom Firmware launch methods are numerous, and as such it is recommended to use this guide over any other that relies on outdated software (such as menuhax + rxTools, arm9loaderhax, or even normal sighax).
For information on how boot9strap works, please see [this presentation](https://sciresm.github.io/33-and-a-half-c3/) by [SciresM](https://github.com/SciresM/).
For a list of each of the calculated sighax signatures (the platform boot9strap is built on), see [this gist](https://gist.github.com/SciresM/cdd2266efb80175d37eabbe86f9d8c52).
## What can I do wit' Custom Firmware?
+ Play all game cards and eShop games, regardless of region
+ **Before beginning the guide, you must know the risks of 3DS hacking: EVERY time you modify your system, there is always the potential for an UNRECOVERABLE brick. They're rare, but still a possibility so make sure you follow ALL directions EXACTLY.**
+ If you have already hacked your 3DS before to get an EmuNAND setup, and would like to move the contents of your previous EmuNAND to your new SysNAND CFW, you should follow all instructions and restore your existing EmuNAND when prompted once you reach [Finalizing Setup](finalizing-setup).
+ If everythin' goes accordin' to plan, ye gunna lose no data 'n be endin' up wit' everythin' that ye started wit' (games, NNID, saves, etc gunna be preserved).
+ Your SD card should be [MBR, not GPT](http://www.howtogeek.com/245610/) (the SD card that comes with your device will be MBR by default).
+ If you need to format a brand new SD card, you can use [`guiformat`](http://www.ridgecrop.demon.co.uk/index.htm?guiformat.htm) and set to an Allocation Unit Size of 32K.