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Introduction to Flow

Flow is a fast, decentralized, and developer-friendly blockchain designed to be the foundation for a new generation of games, apps, and the digital assets that power them. It is based on a unique, multi-role architecture, and designed to scale without sharding, allowing for massive improvements in speed and throughput while preserving a developer-friendly, ACID-compliant environment.

What makes Flow unique​

  • Multi-role architecture: Flow's node architecture allows the network to scale to serve billions of users without sharding or reducing the decentralization of consensus.
  • Resource-oriented programming: Smart contracts on Flow are written in Cadence, an easier and safer programming language for crypto assets and apps.
  • Developer ergonomics: This network is designed to maximize developer productivity. Examples range from upgradeable smart contracts and built-in logging support to the Flow Emulator.
  • Consumer onboarding: Flow was designed for mainstream consumers, with payment onramps catalyzing a safe and low-friction path from fiat to crypto.

The following chapters summarize the content in this section. Read on more for details.

DApp Development​

The development guide covers the Flow core concepts, including:

  • DApp Client: The dApp client is the interface through which users interact with your dApp. Web and mobile applications are typical examples of dApp clients.
  • Smart Contract: A smart contract is a collection of code deployed to a permanent location on the blockchain that defines the core logic for a dApp.
  • User Account: A user account is a record on the blockchain that stores the digital assets owned by a single user.
  • Transaction: A transaction is a code submitted to the blockchain that mutates the state of one or more user accounts and smart contracts.
  • User Wallet: A user wallet is software or hardware that controls access to a user's account on the blockchain.
  • State Query: A state query is a request made to the blockchain that returns information about the state of your dApp's smart contracts.
  • Flow Client Library (FCL): The Flow Client Library is a framework that provides a standard interface to connect client applications and user wallets.

Core Contracts​

The Flow blockchain implements core functionality using its own smart contract language, Cadence. The core functionality is split into a set of contracts, so-called core contracts:

  • Fungible Token: The FungibleToken contract implements the Fungible Token Standard. It is the second contract ever deployed on Flow.
  • Flow Token: The FlowToken contract defines the FLOW network token.
  • Flow Fees: The FlowFees contract is where all the collected flow fees are gathered.
  • Service Account: tracks transaction fees and deployment permissions and provides convenient methods for Flow Token operations.
  • Staking Table: The FlowIDTableStaking contract is the central table that manages staked nodes, delegation, and rewards.
  • Epoch Contract: The FlowEpoch contract is the state machine that manages Epoch phases and emits service events.

FLOW Token​

The FLOW token is the native currency for the Flow network. Developers and users can use FLOW to transact on the network. Developers can integrate FLOW directly into their apps for peer-to-peer payments, service charges, or consumer rewards. FLOW can be held, transferred, or transacted peer-to-peer.