There are a number of blockchain glossaries out there on the web so I don’t want to just copy / paste what they have, so I shall link to some of the better ones on the web but add a few terms which are relevant to Polkadot but less common. The section on “functional components” in the whitepaper provides brief explanations for some key concepts: this article is supplementary to that.

Polkadot Glossary

Bridge, or parachain bridge, is the link between an external blockchain and the relay chain of Polkadot. It would forward the transactions from the external chain and then provide the replies.

Parachain, or parallelised chain, is a data structure hosted upon the relay chain. These structures can be blockchains or something else more general. The term “parachain” certainly suggests that the data should be a chain but that the requirement to be a chain is not so strict according to the whitepaper.

PoC, or Proof of Concept, an example of how something could work. It is a single example out of many possible examples. PoCs are expected to demonstrate how a particular idea works.

Proof of Authority is a consensus mechanism in a blockchain which essentially gives one client with one particular private key the right to make the next block in the blockchain.

Relay Chain is the backbone of Polkadot. It is the central chain to “rule them all”.

RPC, or Remote Procedure Call, is when a computer program causes a procedure to execute on another computer, which is coded as if it were a normal (local) procedure call, without the programmer explicitly coding the details for the remote interaction.

WASM VM,  or WebAssembly Virtual Machine, is the virtual machine of Polkadot which performs the necessary calculations. It allows anyone to execute arbitrary WASM bytecode. It is comparable to the Ethereum Virtual Machine (EVM). Also see WASM.

Node Types

Collator is a type of node that collects transactions for a particular parachain. They maintain a full node and present unsealed blocks of transactions to validators for sealing.

Fisherman is a type of node that monitors and reports upon validator nodes for bad behaviour.

Nominator is a type of node that only has one function: to ‘nominate’ which validator nodes they trust. This is done by placing some dots at risk (staking). Their role is comparable to that of miners in PoW chains.

Validator is a type of node that checks the validity of blocks presented to it by the Collator nodes. It ‘seals’ the blocks to make them ‘final’. These are nodes which make up and secure the relay chain: the central, and most important, part of Polkadot. There is a similarity between validator nodes and mining pools of current PoW chains.


Go is a programming language created at Google back in 2009.

JS, or JavaScript, is a high-level programming language. Alongside HTML and CSS, JavaScript is one of the three core technologies of World Wide Web content production.

Rust is a programming language sponsored by Mozilla Research, which describes it as a “safe, concurrent, practical language,”

WASM, or WebAssembly, is a low-level bytecode format for running scripts inside a web browser. The code runs on the client side, i.e. “in the browser”. It is designed to be faster to execute than Javascript.


Relevant Polkadot Websites

Supplementary Blockchain Glossaries

  1. Ethereum Glossary
  2. Blockchain Glossary: From A-Z (Blockgeeks)
  3. Blockchain Dictionary (Hacker Noon)