This glossary is divided in two sections, the first one concerns Tezos, and the second one concerns the Alpha protocol, which is the current economic protocol.
Along with the payload, the block includes a header which contains protocol-agnostic data. It consists of generic information such as the block predecessor’s hash and the block’s timestamp.
The state of the blockchain. The context is defined by the Economic Protocol and typically includes information such as “this account is credited with this many tez” and “this is the code for that smart contract.”
- Economic protocol
In Tezos, the economic protocol can be upgraded without interruption or forking of the blockchain. The procedure for an upgrade is defined within the economic protocol itself so it can be upgraded as well.
A peer in the P2P network. It maintains a local state and propagates blocks and operations.
- Score (a.k.a. Fitness, a.k.a. Weight)
The score is a metric used to compare contexts. For example, when several blocks claim to be heads of the chain, their context’s scores are compared. The highest scoring block is selected as the head of the chain.
The shell is a software component of the node. It is parameterized by a specific economic protocol. It serves as the bridge between the P2P layer (handling communication between nodes) and the economic protocol layer (handling the context, operation application, scoring, etc.).
When a node attempts to inject several incompatible blocks (or when it tries to abuse the network in another similar way), another node can make an accusation: show evidence of attempted abuse. The node making the accusation is the accuser.
The accuser is awarded some funds from the baking deposit of the accused.
Using the tools provided by Nomadic Labs, accusation is handled by a separate binary.
In the Context, each account is associated with a balance (an amount of tez available).
When a node creates a new block, it is the baker of this block. Baking rights are distributed to different accounts based on their available balance. Only a node that handles an account with baking rights is allowed to bake; blocks created by another node are invalid.
Using the tools provided by Nomadic Labs, baking is handled by a separate binary.
- Baking/Endorsement rights
A delegate is allowed to bake/endorse a block if he holds the baking/endorsement right for that block. At the start of a Cycle, baking and endorsement rights are computed for all the block heights in the cycle, based on the proportion of Rolls owned by each accounts.
For each block height, there are several accounts that are allowed to bake. These different accounts are given different Priorities.
Cycles are used as a unit of “time” in the block chain. For example, the different phases in the amendment voting procedures are defined based on cycles.
An Implicit account to which an account has delegated their baking and endorsement rights. The Baking rights and Endorsement rights are calculated based on the total balance of tez that an account has been delegated to.
- Double baking
When a baker signs two different blocks at the same height, it is called double baking. Double baking is detrimental to the network and might be indicative of an attempt to double spend. As such, it is punished by the network: an accuser can provide proof of the double baking to be awarded part of the baker’s deposit.
When a block is created and propagated on the network, nodes that have Endorsement rights for the matching block height can emit an endorsement operation. The accounts that emit the block are the endorsers of the block. The endorsement operations can be included in the next block to increase the block’s Score.
Using the tools provided by Nomadic Labs, endorsement is handled by a separate binary.
- Implicit account
The address of an Implicit account always starts with the letters tz followed by 1, 2 or 3 (depending on the signature scheme) and finally the hash of the public key.
The built-in language used by a smart contract.
In protocol Alpha, the main operations are transactions (to transfer funds or to execute smart contracts), accusations, activations, delegations, endorsements and originations.
- Originated account
See smart contract.
A rank of different baking rights. Each rank corresponds to a time span. A baker with baking rights at a given priority is only allowed to bake during the priority’s corresponding time span. Baking outside of one’s designated priority, results in an invalid block.
- Smart contract
Account which is associated to a Michelson script. They are created with an explicit origination operation and are therefore sometimes called originated accounts. The address of a smart contract always starts with the letters