Glossary

Candid is a language-agnostic interface description language. It serves the primary purpose of describing a service’s public interface. In the context of the Internet Computer, Candid describes the public interface of a program running as a deployed canister smart contract. Candid enables the inter-operation between front-ends and services that are written in different programming languages, such as Motoko, Rust, and JavaScript.

Canisters are compute units (i.e. an extended version of smart contracts) that are designed for internet-scale applications and services running at web speed. They are powered by cycles. Canister smart contracts can be deterministically run in parallel and have a universally-unique identifier.

Catch-up packages contain all the relevant data required for bootstrapping a subnet replica.

Chain Key Cryptography is a set of cryptographic protocols that are used to orchestrate the node machines hosting the Internet Computer.

A controller is a principal who has been granted special rights for managing canisters under its control. The controller principle can be specified via the principal’s textual representation (also referred to as principal identifier).

Cycles express the cost of computation on the Internet Computer. They act as computational resource that is powering canisters to execute actions on the IC blockchain.

The dissolve delay specifies the amount of time neurons are dissolving before becoming unlocked and accessible again to the neuron holder.

The governance canister is responsible for implementing the governance system of the Network Nervous System. It is a system canister tasked with storing and managing neurons/proposals as well as implementing governance votes.

The ICP is an advanced fault-tolerant, cryptographic protocol. It ensures that the smart contracts running on the Internet Computer blockchain cannot be stopped or tampered with.

Internet Identity is a blockchain authentication system that allows users to access dApps on the Internet Computer securely and anonymously. Internet Identity empowers users to authenticate themselves without the need for usernames and passwords.

The so-called ledger canister is a specialized management canister that records all transactions on the Internet Computer blockchain involving ICP tokens. It is a special smart contract for maintaining accounts and balances and for keeping a transaction history. The following event types are tracked by the ledger canister:

Motoko is the native programming language of the Internet Computer. It is a type-safe and modern programming language designed for developers who wish to build the next generation of dApps on the Internet Computer. Motoko enables developers to use the unique features of the IC.

The Network Nervous System (NNS) is the governance system of the Internet Computer and is responsible for orchestrating the decentralized decision-making process that controls and manages the network. Its open governance system oversees – among other things – the permission to participate in the network.

Network participants need to lock up their ICP utility tokens by creating a neuron to vote on governance proposals. A neuron represents ICP tokens that cannot be exchanged or transferred during the predetermined lock-up period.

Nodes are virtual or physical machines hosting the hardware, software, as well as the configuration settings required to operate the Internet Computer blockchain. They are hosted in independent data centers and run by independent node operators.

Principals are entities that the Internet Computer Blockchain can authenticate. Principals interacting with the protocol often use an identity to do so. For example, users of the DFINITY Canister SDK receive a default developer identity with a public/private key pair from the dfx command-line tool.

The term replica refers to the protocol processes of the Internet Computer that are running on a node machine.

Unlike other blockchains, end users are not charged for interacting with the Internet Computer. Instead, developers precharge their canister smart contracts with so-called “cycles” by converting the ICP token to cycles. This model makes the Internet Computer seamlessly accessible for end-users that do not have to own ICP, cycles, or any other cryptocurrency to interact with the IC.

Subnets are clusters of node machines hosted in different data centers around the world. Subnets are responsible for hosting the Internet Computer’s canister smart contracts.

A wallet, such as the NNS front-end dApp, is a decentralized application hosted on the Internet Computer as a canister allowing its users to store and manage ICP tokens and cycles.

WebAssembly, also know as Wasm, is a low-level, binary instruction format that finds its application in a stack-based virtual machine. WebAssembly is broadly supported by programs running on the internet as it defines a portable binary format which cleanly abstracts over modern computer hardware.