What is subdomain cookie consent?

Subdomain cookie consent is the technical method used to share a stored consent preference across related subdomains.

For example:

1. A visitor chooses preferences on www.example.com.

2. The consent cookie is scoped to the parent example.com domain.

3. shop.example.com and other permitted subdomains can read the same preference.

This behavior is controlled through the cookie's Domain attribute. When a parent domain is specified, the cookie can be available to its subdomains; if the attribute is omitted, the cookie is normally limited to the host that created it.

A cross-subdomain consent implementation can share the technical preference, but it cannot expand the legal scope of what the user originally accepted.