Protocol may refer to:

• Protocol (diplomacy), the etiquette of diplomacy and affairs of state
• Etiquette, a code of behavior
• Minutes, also known as protocols, the written record of a meeting

• Protocol (object-oriented programming), a common means for unrelated objects to communicate with each other (sometimes also called interfaces; related to duck typing)
• Protocol (science), a predefined written procedural method of conducting experiments
• Communication protocol, a defined set of rules and regulations that determine how data is transmitted in telecommunications and computer networking
  • Cryptographic protocol, a security protocol for encrypting messages
• Medical protocol (disambiguation)

• Proprietary protocol, a communications protocol owned by a single organization or individual
• Quantum cryptography protocol, a protocol for encrypting messages