Glossary of Terms

Term	Description
Archive Node	Archive nodes support analytics use cases and research. They do not participate in the validation or processing of new transactions or blocks. Instead, they store every transaction that has ever occurred on the blockchain network, including previous versions. Tracing data isn't commonly found, although some implementations can enable this functionality.
Authority Node	Same as a validator (this term is mainly used by Parity).
Blockchain	A blockchain is a shared ledger where appending blocks permanently record transactions. The blockchain serves as a historical record of all transactions that ever occurred, from the genesis block to the latest block, hence the name blockchain.
Block Explorer	Block Explorer is an online tool to view all transactions, past and current, on the blockchain. They provide useful information such as network hash rate and transaction growth.
Block Height	The number of blocks connected on the blockchain.
Block Reward	A form of incentive for the miner who successfully calculated the hash in a block during mining. Verification of transactions on the blockchain generates new coins in the process, and the miner is rewarded a portion of those.
Byzantine Fault Tolerance	A property of a consensus algorithm that ensures that this consensus algorithm can tolerate arbitrary (including malicious) node failures.
Consensus	Consensus is achieved when all participants of the network agree on the validity of the transactions, ensuring that the ledgers are exact copies of each other.
DAO	Decentralized Autonomous Organizations can be thought of as corporations that run without any human intervention and surrender all forms of control to an incorruptible set of business rules.
dApp	A decentralized application (dApp) is an application that is open source, operates autonomously, has its data stored on a blockchain, is incentivized in the form of cryptographic tokens, and operates on a protocol that shows proof of value.
Delegation	The ability to provide coins/tokens to a stake pool allowing participation in staking without the need of a user to operate their own node.
Double Signing	When a validator signs two blocks simultaneously, usually as a result of a backup node issue. This is one of the conditions that can lead to slashing.
Downtime	Refers to a validator’s absence to sign transactions on a blockchain for a certain time. Expectations for a validator’s uptime differ from one protocol to another. This is one of the conditions that can lead to slashing.
Difficulty	This refers to how easily a data block of transaction information can be mined successfully.
Distributed Ledger	Distributed ledgers are ledgers in which data is stored across a network of decentralized nodes. A distributed ledger does not have to have its own currency and may be permissioned and private.
Distributed Network	A type of network where processing power and data are spread over the nodes rather than having a centralized data center.
Fail-stop Fault Tolerance	A property of a consensus algorithm that ensures that this consensus algorithm can tolerate nodes that crash.
Federated BFT	A special version of BFT that allows it to be used in big public blockchains; Anybody can become a validator, but nodes decide which validators they trust; Examples: Stellar.
Full / Current Node	Full nodes verify and add new transactions and blocks to the blockchain. They maintain a complete copy of the blockchain's current state but don't store previous versions. Some implementations contain tracing data by default, while others may need to have this feature enabled.
Genesis Block	The first or first few blocks of a blockchain.
Gnosis Safe	Multisig wallet that controls the admin functionalities of the smart contract. Owners are both Stakewise and Blockdaemon team members.
Hard Fork	A type of fork that renders previously invalid transactions valid, and vice versa. This type of fork requires all nodes and users to upgrade to the latest version of the protocol software.
History / Historic Node	Historic nodes facilitate access to specific subsets of data without actively participating in the validation or processing of new transactions or blocks. They maintain a subset of the blockchain's historical data, which can vary based on implementation. They may not contain tracing data by default, but some versions can enable this feature.
Hybrid PoS/PoW	A hybrid PoS/PoW allows for both Proof of Stake and Proof of Work as consensus distribution algorithms on the network.
Keeper	A keeper is a specially configured Oracle that collects data from all Oracles and submits them to the smart contract.
Light Node	Light nodes are quicker and more responsive than full nodes but rely on the integrity of other nodes. They don't store a full copy of the blockchain ledger, instead storing only a subset of information necessary to validate a transaction with full or archive nodes. It's uncommon for them to contain tracing data.
Miner	Same as a validator; Mostly used in the context of PoW.
Mining	Mining is the act of validating blockchain transactions. The necessity of validation warrants an incentive for the miners, usually in the form of coins.
Mining Node	Mining nodes create new blocks on a Proof-of-Work (PoW) blockchain by solving complex mathematical problems. They broadcast new blocks for validation and addition to the network's ledgers. They store only enough recent blocks and transactions for ongoing participation, with some running a full or archive node to retrieve older data. Tracing data is usually absent.
Node	A copy of the ledger operated by a participant of the blockchain network.
PBFT	Practical Byzantine fault tolerance; A consensus algorithm to implement PoA.
Permissioned Blockchains	Another term for PoA.
PoA	Proof of authority; Validators are pre-selected upfront; Adding/removing validators typically happens by voting (i.e. if a majority of existing validators agree to add a new validator); Examples: Private Ethereum; Quorum, HLF.
PoR	Proof of reputation; Used by GoChain; Same as PoA, but only big players (that have a reputation to lose) are allowed as validators.
PoS	Proof of state; Anybody can be a validator as long as they “stake” enough coins; Suitable for big public blockchains; Examples: Public Ethereum (once they switch to PoS).
PoW	Proof of work; Anybody can be a validator as long as they solve the PoW challenge; Suitable for big public blockchains; Examples: Public Bitcoin, Public Ethereum.
Private Blockchain	Only a selected group can listen to the blockchain – Typically, these blockchains use PoA. Note that even though the blockchain itself is private to outside “eyes”, anybody who can see the blockchain still can see all transactions.
Private Key	A private key is a string of data that allows you to access the tokens in a specific wallet. They act as passwords that are kept hidden from anyone but the owner of the address.
Private Transactions	Some Blockchains (Quorum, HLF) allow sending some transactions “privately”. Only the receiver of the transaction can see the content.
Public Address	A public address is the cryptographic hash of a public key. They act as email addresses that can be published anywhere, unlike private keys.
Public Blockchain	Anybody can listen to the blockchain – Note that this can be implemented with PoA, PoS, and PoW.
rETH2	Stakewise (permissionless) staking token.
rETH2-h	Portara reward token
Reward	Compensation for the provision of tasks/roles critical to the functioning of the protocol e.g. operating a validator and producing blocks (block rewards), depositing the minimum staking requirement for a validator (staking rewards), the operation of a pool and/or provision of significant liquidity (liquidity mining rewards).
Sealer	Same as a validator, but I see this term more often in the context of PoS.
Seed Node	Seed nodes assist new nodes in joining the network and discovering peers, particularly in peer-to-peer (P2P) networks and some blockchain protocols. They possess a fixed IP address or domain name hardcoded into the client software of other nodes. They store limited metadata, such as IP addresses and connection information. It's uncommon for them to contain tracing data.
sETH2	Stakewise (permissionless) staking token.
sETH2-h	Portara staking token.
Slashing
Smart Contracts	Smart contracts encode business rules in a programmable language onto the blockchain and are enforced by the participants of the network.
Solidity	Solidity is Ethereum’s programming language for developing smart contracts.
Stakewise Oracle	A component within the Stakewise/Portara systems that is responsible for managing validators and calculating rewards.
SWISE	Stakewise (permissionless) governance token.
Transaction Fee	All cryptocurrency transactions involve a small transaction fee. These transaction fees add up to account for the block reward that a miner receives when he successfully processes a block.
Validator	A node that’s allowed to create new blocks in a PoA blockchain.
Validator Node	Validator nodes create new blocks on a Proof-of-Stake (PoS) blockchain through staking and consensus, also validating transactions. Storage varies, but they usually mirror full or archive nodes. They commonly include tracing data by default.
Watcher Node	Watcher nodes monitor the network's state and track specific events or transactions without participating in the consensus process or transaction validation. They store only enough information to respond to current state changes, with the exact amount varying per implementation. Tracing data is not typically included.
Yield	Profit of users of the system that can be realized by financially investing in and/or interacting with the public interfaces of it e.g. lending of limited amounts/worth of tokens, delegating stake to validators (delegated staking rewards), receiving airdrops, etc This can be a positive or negative value - negative when there’s been a slashing event.