A third-party refers to an individual, organization, or entity that is not directly involved as a principal in a particular transaction, agreement, or relationship, but may be affected by it or play a supporting role. In business and technology contexts, third-parties often provide products, services, or software that integrate with or complement those of the primary parties. For example, a payment processor handling transactions for an online store is considered a third-party. The involvement of third-parties can introduce additional considerations for security, privacy, and compliance.