Privacy & regulation · also called GPC
Global Privacy Control (GPC)
Global Privacy Control (GPC) is a browser or extension setting that automatically tells every website a user visits that they do not want their personal data sold or shared.
Instead of clicking "do not sell" on every site, a user can switch on GPC once. Their browser then sends a signal, an HTTP header and a JavaScript property, with every request, expressing an opt-out of sale and sharing. Some browsers and privacy extensions offer it built in.
The legal weight comes from laws that recognise it. California's CCPA / CPRA regulations require businesses to treat GPC as a valid opt-out of sale and sharing, and the California Attorney General's 2022 Sephora settlement cited failures to honour it. Colorado and several other US states have similar universal opt-out requirements.
For ad tech, honouring GPC means detecting the signal, treating the user as opted out of cross-context behavioural advertising, and passing that choice downstream, typically via a CMP and the IAB Global Privacy Platform string. GPC is not a consent mechanism for European law; under GDPR, consent is still collected actively. It succeeded the earlier, voluntary "Do Not Track" signal, which lacked legal force and was widely ignored.
Think of it like this
GPC is like a "no junk mail" sticker on your letterbox that, in some places, the law says every sender must obey.
An example
A visitor from Colorado browses with GPC turned on. The publisher's CMP detects it, writes an opt-out into the GPP string and its SSP stops passing her identifiers to DSPs for targeted ads.
Related terms
CCPA / CPRA
The CCPA, as amended by the CPRA, is California's consumer privacy law giving residents rights to know, delete, correct and opt out of the sale or sharing of their personal information.
IAB Global Privacy Platform (GPP)
The IAB Global Privacy Platform (GPP) is an IAB Tech Lab standard that packages privacy and consent signals for many jurisdictions, like US states and the EU, into one string.
CMP (consent management platform)
A CMP (consent management platform) is software that shows users privacy choices, such as a cookie banner, records their consent or opt-outs, and passes them to the site's partners.
Behavioral targeting
Behavioral targeting shows ads to people based on their past online behaviour, such as sites visited, searches, purchases or app use, collected over time and often across different services.
Consent string
A consent string is a compact encoded value recording a user's privacy choices, such as the TCF TC String or a GPP string, that travels with ad requests to vendors.
Sources: Global Privacy Control, California Attorney General: CCPA regulations