Third-party opt-in refers to the process of obtaining explicit consent from an individual to share their personal information with a third-party for marketing or other purposes. This means that the individual has actively given permission for their data to be shared, rather than it being collected and shared without their knowledge or consent. This type of opt-in is often used by businesses and organizations to ensure transparency and respect for the privacy of their customers or users. It allows individuals to have control over how their data is used and who it is shared with, promoting a sense of trust and accountability in the digital world.