Definition of "opt-in" []

• Of a selection, the property of having to choose explicitly to join or permit something; a decision having the default option being exclusion or avoidance; used particularly with regard to mailing lists and advertisement. (adjective)

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• "In the United States, as in many countries, we rely on a simple system of altruism, or what might be called the opt-in approach."
• "While privacy is a big issue in the online consumer business, it is a moot point in the Groupon world, because customers voluntarily and explicitly sign up to be targets otherwise known as "opt-in"."
• "In a hearing in New York last month, Judge Chin asked representatives of Google, the Association of American Publishers and the Authors Guild whether it might be possible to negotiate a so-called opt-in agreement - in other words, along the lines of the Hachette deal."