What may be the most talked about feature in iOS 9 is a new class of application called a Content Blocker. These apps work within Safari to block ads, tracking scripts, comments, adult sites, etc... Generally all the crud that slows down and gums up our web browsing experience. I won't try to tackle the ethical implications of blocking legitimate ads that pay the bills for many of our favorite blogs. Everyone else can determine that for themselves. Instead, I'll focus on the positive aspects for all us parents.
If you have a kid who uses an iDevice, then you need to upgrade to iOS 9 and download one of these tonight. For a few bucks, you can block advertisements of all kinds, specific sites, and adult content from your kids device. That is simply a no brainer. One caveat though: you must be using iPhone 5s and newer, iPad Mini 2 and newer, iPad Air and newer, or iPod Touch 6th generation.
Crystal - Block Ads, Browse Faster. - Dean Murphy
1Blocker - Block ads, tracking scripts, anything - Salavat Khanov
Once you install a content blocker, go to Settings > Safari and scroll down to Content Blockers. Flip the switch to enable/disable your content blocker(s) of choice.
Please do not take these as an end to the need for monitoring what your kids may be up to on their devices. Even those that purport to block adult sites do not catch it all. It is up to you to make sure these apps download their updates as available. Consider this a great start.