YouTube, mindful that it's tough to police the hours of video that are uploaded to its site every minute, has introduced a new feature titled "Safety Mode". This is a switch, a bit like Google's "Safe Search", which aims to prevent objectionable content from being displayed on the site.
The setting is opt-in - to activate it, scroll down to the bottom of any video page and hit the "Safety Mode" link. You'll then get a little more information and the ability to turn it on and off. Then certain content will be filtered - Google offers the examples of graphic footage in war coverage, or the word "naked". Words that Google considers "objectionable" will also be censored from the comments section, replaced with asterisks.
All videos, even those that display outside of safety mode, still have to comply with YouTube's community guidelines, but this is an extra layer of content filtering for those who are especially concerned.
The feature is rolling out across YouTube at the time of writing, so you might not see it immediately. If you don't, then check back in a couple of days and you should have access.