Solidity is a high-level, object-oriented programming language created for designing and implementing smart contracts.^[3]

Overview

Solidity is a contract-oriented programming language designed by the Ethereum Network team for implementing smart contracts. It draws inspiration from programming languages like C++, Python, and JavaScript, and interacts with the Ethereum Virtual Machine.^[1]

Basic concepts of Solidity revolve around enabling developers to create decentralized applications (DApps) and self-executing contracts on blockchain networks.

Solidity Compiler v0.8.27 was released on September 4, 2024.^[5]

Main characteristics:

• Statically-typed: Solidity prevents mistakes, such as syntax and type errors, by verifying that every variable in the source code has a data type before it is executed to ensure that the application operates smoothly.
• Contract-oriented: The programming language is designed to create smart contracts, which are self-executing contracts containing terms of agreement written into lines of code. These contracts can be used to create decentralized applications (DApps) and execute transactions on the Ethereum network.
• Object-oriented: Solidity uses objects (data structure or self-contained units of code) to present data and their behavior to allow developers to organize code in a structured and modular way.^[1

Fundamental concepts

Following are some fundamental concepts of Soliidty.^[3][4]

• Smart Contracts
  Smart contracts are self-executing agreements with the terms of the contract written in code. Solidity is used to create these contracts, defining their rules, conditions, and actions.

• Data Types
  Solidity supports various data types, including integers, booleans, addresses, and more, similar to other programming languages. Developers use these types to declare and manipulate data in smart contracts.

• Functions
  Smart contracts consist of functions that define the contract’s behavior. These functions can be called internally or externally, enabling interaction with the contract.

• Variables
  Solidity allows the declaration of state variables to store data permanently on the blockchain. These variables maintain their values across function calls.

• Events
  Events are a way for contracts to communicate with external applications, allowing them to subscribe to and react to specific occurrences within the contract.

• Inheritance
  Solidity supports contract inheritance, enabling the creation of modular and reusable code.

• Ethereum-specific Concepts
  Solidity integrates Ethereum-specific concepts like gas (transaction fees), ether (cryptocurrency), and the Ethereum Virtual Machine (EVM), which is responsible for executing smart contracts.

• Security
  Security is a critical consideration in Solidity. Developers must understand vulnerabilities like reentrancy, integer overflow, and more to write secure contracts.

Solidity is available on smart contracts including:^[6]

• Ethereum

• Avalanche C-Chain

• Binance Smart Chain

• Counterparty

• Ethereum Classic

• Tron

• Hedera Hashgraph

• Polygon

• Metis

• Arbitrum

• Optimism

Advantages and Drawbacks of Solidity Programming Language

Advantages

• Enables flexibility by allowing developers to create custom data structures, functions, and complex smart contracts.

• Provides an interface, known as Application Binary Interface (ABI), that allows type safety to signal that there’s an error whenever there’s a mismatch in the data type of a variable. ABI is a set of rules and specifications that define how a smart contract can interact with other smart contracts.

• Translates user-oriented requirements and specifications into a language that can be understood by machines.

Drawbacks

• The language is vulnerable to reentrancy attacks, which occur when a contract allows a malicious user to repeatedly call a function in such a way that the contract’s state is exploited.

• Blockchain’s immutable nature ensures that a smart contract, once deployed, cannot be modified or removed. Because of this, it’s crucial to make sure that every single line of code is flawless to prevent the risk of exploitation or hacking.

• Solidity has arithmetic precision issues, where the language does not support fixed or floating-point values.