Can I remove MicroSD card with my Android phone turned on? On my Samsung Galaxy 551 I can remove the MicroSD card without needing to remove the battery and consequently turn off my cellphone. Should I remove my SD without turning off the phone? Will I damage something if I do it?
You should first dismount the card.  You can do this via Settings -&gt; SD card and phone storage -&gt; Unmount SD card.  You can certainly corrupt data and cause application crashes if you don't do this first.