Apple's differential privacy in iOS 10 is opt-in, limited to four use cases

The new data collection method set to roll out in iOS 10 will require users to opt in, and will be limited to four specific system functions, according to Apple.

Those include new words added to local dictionaries and emojis entered by users, the latter so that Apple can suggest emoji replacements, the company explained to Re/code. The other two are deep links within apps, as long as they're marked for public indexing, and lookup hints inside Notes.

All four are being safeguarded by differential privacy, a concept that introduces "noise" into big data so that broad trends can be analyzed without making it possible to identify individual sources. Apple first announced its use of the technology when it revealed iOS 10 at last week's Worldwide Developers Conference in San Francisco.

The company has often railed against data collection when attacking competitors like Google, and indeed many of the predictive functions in iOS 9 and 10 are processed entirely on-device for this reason.

Other companies — including Google — have implemented differential privacy in the past, but Apple's use is believed to be the first on a wide scale.