As most users are expected to decline, the moves have drawn the ire of tech giants who fear a loss of advertising revenues, including Facebook.
As of Monday evening, after upgrading to version iOS 14.5, Apple users will be able to decide whether or not their apps can track them for marketing purposes.
Announced last year, Apple's App Tracking Transparency (ATT) tool has already drawn significant criticism from online advertising companies - especially Facebook - as well as media companies.
Facebook CEO Mark Zuckerberg accused Apple of using ATT to pursue only its own business goals and cutting off free apps financed by advertising to earn money though paid apps and paid software from its store.
Right to privacy
Apple responded to the complaint saying, "We believe privacy is a fundamental human right," and that data belongs to users who should be able to decide how their data is used.
ATT is just one part of a broader privacy initiative by Apple.
App providers have also had to publish a privacy label when submitting or updating their app for the first time. The feature lists all the kinds of data gathered by the app, resembling a list of ingredients on food.