A new California law requires operating system providers to implement age verification at account setup, which will provide a signal to applications regarding the user's age bracket. The law applies to all operating systems, including Linux, and requires providers to collect age verification information and pass it to developers upon request. The law is set to take effect on January 1, 2027, and its enforcement and impact on the tech industry are still uncertain. Some operating systems, like Windows, already collect age information during account setup, but others may need to adapt to comply with the law.