Originally Posted by mattg3
What exactly is or does the .nomedia file do?
the .nomedia stops any media file (pictures, video or music) in the folder its in and all sub folders from being being scanned in the "media scanning" that occurs everytime you boot up (when you have 20+ GB on an SD card it takes a minute or 2 to scan at every boot up before you can start your music) or unplug your android device from a computer. the issue is most players get there tracklist from that scan so if you stop it you have no music in those players, but poweramp has its own library scanner you can run only when needed.
Also, I've read that the media scanner in android won't list music when there are certain things wrong with the id3 tags, which I can vouch for the poweramp library scanner finds like 20+ more songs then the media scanner.
Why use this .nomedia, well if you have "in folder" album art all those images will show up in the default photo gallery unless you use it to block the scanning of those folders.