# Protocol versioning¶

The protocol is the part of the node software that provides logic for executing transactions and building blockchain blocks. It embodies all the rules that a Tezos network operates under. Therefore changes to the protocol must be explicitly accepted by the community before nodes actually employ them. For this reason the protocol is versioned independently from the rest of the software engaged in running Tezos. Each protocol version is being proposed to the community for acceptance. The community then decides whether to accept the new protocol or keep the old one. This is done through a voting procedure, which takes place within the blockchain itself, so its rules are also a part of the protocol.

## Protocol naming¶

The protocols that have been used in the past are versioned by an increasing sequence of three-digit numbers, starting with 000. From protocol versioned 004 upwards, each protocol version is traditionally named after an ancient city (using anglicised name), where the first letters form an alphabetical order sequence:

• 000 Genesis

• 001 Alpha-I

• 002 Alpha-II

• 003 Alpha-III

• 004 Athens

• 005 Babylon

• 006 Carthage

• 007 Delphi

• 008 Edo

Due to the evolving nature of the in-use protocols, the above absolute protocol names are not enough. More naming conventions are introduced for the currently in-use and upcoming protocols:

• The protocol in the src/proto_alpha directory of the master branch: “alpha protocol”

• other terms: “protocol under development”, “development protocol” (only when there is a single one)

• The currently active protocol: “current protocol”.

• other terms: “active protocol”, “mainnet protocol”

• The protocol currently under voting, that is in any of the possible voting phases: “candidate protocol”.

• other possible terms: “current proposal”

## External resources¶

The current protocol status can be found at tz-stats.com election page.

An interesting blog post on the history of the initial Tezos economic protocols is: A quick history of past upgrades.