If the DVDs, USB sticks, phones, cameras or any other media and devices are automatically starting to play or open explorer windows and your don't want them to, this is how you tweak the AutoPlay settings.
If your phone doesn't want to boot up again after the update, it gets stuck in a black screen, follow this tutorial where we root the Galaxy SII with Odin and put an official Samsung Android 4 ICS on it.
If you are a "private" person and don't want your profile picture or name to appear on your friend's feed next to ads you liked, then follow this steps.
If you don't want others to use your photos and images without your permission, you can create a so called custom watermark with your name or any other text you want.