Various third-party browsers have been available with the ability block ads for iOS, but this time around, Apple has integrated the feature directly into Safari.
It not only removes ads you may not want to see; it also speeds up the mobile browsing experience noticeably. Sites that used to take 10 seconds or more to fully render on my iPhone are now loading in a second or two.
First you have to install one. Crystal is freely available now for a limited time -- as is Purify although it costs $3.99 -- so I downloaded it to my iPhone 6 after installing iOS 9. That's not enough though: You have to enable the blocker.
To do so, go into the iOS Settings and tap the icon for Safari. Scroll down to the "Content Blockers" option and tap it. Any content blocking apps you have installed will then appear and you simply need to move the slider to enable one or all of them.
It's that simple. And it's effective based on some quick testing I did while browsing multiple, ad-heavy sites.