Protocol may refer to:

• Protocol (politics), a formal agreement between nation states
• Protocol (diplomacy), the etiquette of diplomacy and affairs of state
• Etiquette, a code of personal behavior

• Protocol (science), a predefined written procedural method of conducting experiments
• Medical protocol (disambiguation)

• Protocol (object-oriented programming), a common means for unrelated objects to communicate with each other (sometimes also called interfaces)
• Communication protocol, a defined set of rules and regulations that determine how data is transmitted in telecommunications and computer networking
  • Cryptographic protocol, a protocol for encrypting messages
• Decentralized network protocol, a protocol for operation of an open source peer-to-peer network where no single entity nor colluding group controls a majority of the network nodes

• Protocol (album), by Simon Phillips
• Protocol (band), a British band
• "Protocol", a song by Gordon Lightfoot from the album Summertime Dream
• "Protocol", a song by the Vamps from their 2020 album Cherry Blossom

• Protocol (film), a 1984 comedy film
• Protocol (website), an offshoot of Politico
• Minutes, also known as protocols, the written record of a meeting
• Protocol (news), a news website owned by Capitol News Company

• Proprietary protocol, a communications protocol owned by a single organization or individual
• Proto (disambiguation)
• Quantum cryptography protocol, a protocol for encrypting messages
• The Protocols of the Elders of Zion, a notorious antisemitic hoax that has circulated since the early 20th century