For questions concerning the device firmware (as opposed to e.g. the 'radio-firmware'). See the full tag wiki for details, explanations, and hints.
What is device firmware?
Wikipedia describes the term "firmware" as the combination of persistent memory and program code and data stored in it. When it comes to Android, several terms often seem to have (at least) double meanings -- so what is firmware actually referring to?
First, it could be the radio-firmware, which is really the lowest level of firmware for our devices. One can think of that as an "hardware abstraction layer", or a kind of "Bios" (in fact, the Wikipedia page on BIOS links to Firmware for the "general concept" of a bios).
So why different tags for the same thing?
If you hover your mouse over the rom tag, you will find it is used for firmware images. This is the aspect the end-user cares most about: Getting the newest stuff on his device. rom is for the package with this "stuff" to be flashed to your device (hence rom-flashing, nothing with "firmware-flashing", and stock-rom, custom-rom, or the generic rom for the images, the "special packaging" if you want so.
Still confused. What should I use when?
- device-firmware: generic firmware questions
- radio-firmware: for questions concerning the radio firmware, as described above (do just not confuse this with some fm-radio to listen to ;)
- rom: generic ROM questions. Please check its tag wiki for closer information on the following related tags, especially for a list of specific custom-rom-tags
- rom-flashing: questions concerning the "flashing" (i.e. installation] of ROM images -- regardless of stock, custom, radio, whatever.
- custom-rom: questions specific to custom-roms as such (or to a specific custom ROM not having its own tag)
- stock-rom: questions on stock-ROMs (i.e. the "original ones" from the manufacturers/providers)