Interpolation in the context of digital marketing is a programming technique used to dynamically insert, or interpolate, specific data or content into a predetermined format or template. This is often used in email marketing, web development, and advertising to personalize content based on user data, preferences, or behavior. For instance, in an email campaign, interpolation allows for personalizing emails with the recipient's name, location, or other specific details, enhancing the relevance and engagement of the content.