Whether or not you live in California, you've likely received something in your inbox about new privacy notices from one of the various companies you've interacted with, such as Lyft, Spotify and Hulu.

That's thanks to the California Consumer Privacy Act, which went into effect on Wednesday, Jan. 1, and deals with how large companies are allowed to collect and use data of California residents. It gives California consumers the ability to request personal data be deleted from a given company, among other protections. The law will make it harder for companies to collect and manage the kind of data about consumers that has powered digital advertising for years.

Businesses are subject to CCPA if they meet the requirements of having gross annual revenues of more than $25 million; buy, receive or sell the personal information of 50,000 or more consumers, households or devices in California; or derive 50% or more annual revenue from selling consumers' personal information. The company doesn't need to be in California but is subject to the law if it collects personal information on that threshold of residents there.

Though the law went into effect Wednesday, it technically isn't being enforced yet. Sarah Lovenheim, special assistant for strategic communications for California Attorney General Xavier Becerra's office, said businesses that meet the thresholds spelled out under CCPA "should be prepared to adhere to the law now." For noncompliance, companies will be required to pay $2,500 per violation if unintentional and $7,500 if intentional.

"While we can't take action until six months after finalizing our rules, or July 1 — whichever comes first — we can consider a business's efforts to comply with the law from January 1, onwards," she wrote in an email to CNBC. The rules are technically subject to change until comments are considered. Businesses and other parties were able to submit comments about the regulations during public hearings, by mail or over email until last month.

And a lot of data is at stake. According to estimates in the Standardized Regulatory Impact Assessment for the law, CCPA will protect more than $12 billion worth of personal information that's used for advertising in California each year.

Unsurprisingly, ad industry groups have pushed back against the law. The Association of National Advertisers, the American Association of Advertising Agencies, the Interactive Advertising Bureau, the American Advertising Federation and the Network Advertising Initiative, some of the most powerful and influential trade groups for the industry, provided written comments last month.

The groups cited concerns about negative consequences proposed regulations could create for consumers and businesses. They said they were concerned the rules' provisions "impose entirely new requirements on businesses that are outside of the scope of CCPA and do not further the purposes of the law."