Quickex team
April 5, 2024
~5 min read

What is a Smart Contract?

Smart contracts automate and secure transactions on the blockchain, providing transparency and efficiency by eliminating intermediaries. Encoded directly into the blockchain's immutable code, they guarantee performance when certain conditions are met.

What is a Smart Contract?

Smart contract is a self-executing contract whose terms and fulfillment are fully encoded and stored on the blockchain. This innovative approach to contracting enables transactions without the need for intermediaries, making the process more transparent, secure and efficient. Thanks to blockchain technology, smart contracts become immutable and immune to external interference once activated, ensuring secure and autonomous execution of agreements.

Quickex facilitates access to innovative smart contract solutions, allowing users to not only exchange cryptocurrencies in a secure environment, but also explore the potential of blockchain technology to create decentralized applications and automate financial transactions.

History and definition of smart contract

The term "smart contract" was first coined by Nick Szabo, a lawyer and computer scientist, in the early 1990s. Szabo described smart contracts as computerized transactional protocols that enforce the terms of a contract. He saw them as having the ability to greatly enhance the functionality of traditional contracts by incorporating digital technology, making them more automated, self-sufficient and secure.

The concept of smart contracts allows two or more parties to enter into contracts in the form of program code that are automatically executed when predetermined conditions occur, without the need for intermediary intervention. This is achieved through the use of blockchain technology, which provides transparency, security and immutability of transaction records.

Sabo used the analogy of a vending machine to visualize how smart contracts work. In this example, the vending machine acts as a self-executing contract: when the customer deposits money, the machine automatically dispenses the goods. The entire transaction takes place without the participation of third parties, and its outcome depends entirely on the fulfillment of predefined conditions (if the amount is deposited, the goods are dispensed). The same way smart contracts work on the blockchain: the contract code independently executes the agreement between the parties as soon as all the conditions of the contract are met.

This revolutionary idea formed the basis for the creation of modern smart contracts on blockchain platforms such as Ethereum, enabling complex decentralized applications and automating a wide range of economic interactions in the digital world. Smart contracts have opened up new opportunities for developers and entrepreneurs, creating limitless prospects for innovation in finance, logistics, law and many other areas.

Smart contracts vs. traditional contracts

Smart contracts and traditional contracts serve the same purpose - to create an agreement between the parties. However, their enforcement mechanisms differ significantly, providing unique advantages and challenges.

Enforcement mechanisms

Traditional contracts require the involvement of lawyers, notaries and sometimes the court system to ensure that both parties fulfill the terms of the contract. This not only incurs additional costs, but also significantly slows down the contract execution process.

Unlike traditional contracts, smart contracts are automatically executed thanks to code embedded in the blockchain. Once the terms of a smart contract are met, it automatically proceeds to execution without the need for external confirmation or third-party intervention.

Benefits of smart contracts:

  • Immediate Execution: One of the key advantages of smart contracts is their ability for immediate execution. Once the terms of the contract are met, execution happens automatically, saving time and speeding up transactions.
  • No need for intermediaries: Smart contracts eliminate the need for intermediaries such as banks, lawyers and notaries to fulfill agreements. This not only reduces transaction costs, but also reduces reliance on external services that can add additional layers of complexity and potential points of failure.
  • Transparency and security: The records of smart contracts are stored on the blockchain, providing a high level of transparency and security. Every transaction is verified and recorded on the blockchain, making it virtually impossible to alter or tamper with executed contracts without the consent of all participants in the network.
  • Legal services: While smart contracts can simplify many aspects of contract formation and execution, they cannot always replace traditional legal services, especially in complex cases requiring interpretation of the law. However, in many standard and repetitive transactions, smart contracts offer an effective solution without the need for legal counsel.

Smart contracts on the blockchain

Unlike Bitcoin, which was originally developed as a digital currency system, Ethereum introduced the concept of smart contracts as a core feature of its network, allowing developers to create complex decentralized applications (DApps) directly on the blockchain.

Smart contracts on Ethereum

Ethereum has provided a more flexible and powerful platform for smart contracts compared to Bitcoin. Smart contracts on Ethereum are written in the Solidity  programming language and deployed on the blockchain as decentralized applications. These applications can perform a wide range of functions without intermediaries, from creating digital tokens and voting systems to automatically managing resources and executing transactions in financial markets.

An example of the use of smart contracts on Ethereum is the Golem project. Golem creates a marketplace for computing power where users can "rent" excess power from their computers to other users in need of additional computing power, which utilizes smart contracts. These smart contracts automatically process transactions between tenants and landlords, providing security and reliability without the need for a centralized intermediary.

Smart contracts on Bitcoin

Although the Bitcoin blockchain was not originally designed for complex smart contracts, it supports basic smart contracts through the Script mechanism. Script is a simple programming language that is used to create conditions under which bitcoins can be spent. These conditions are usually limited to certain types of transactions, such as multi-signature or time-based transactions, and don't offer as much flexibility as smart contracts on Ethereum.

Other blockchain platforms for smart contracts

Apart from Ethereum, a host of other blockchain platforms also support smart contracts. For example, EOS, Cardano and Tezos offer various improvements in terms of scalability, transaction speed, and programming language flexibility, making them attractive alternatives for developers of DApps.

Limitations of smart contracts

These limitations must be considered when developing and using smart contracts:

Problems with code changes

One of the key limitations of smart contracts is that they are immutable once deployed on the blockchain. While this provides a high level of security and reliability, it also means that any errors or vulnerabilities in the code of a smart contract cannot be easily fixed once it has been activated. This creates security risks, especially if the contract contains critical bugs that can be exploited by attackers. Changing a contract requires creating a new version and migrating all existing data and assets, which can be a complex and risky process.

Interaction with the real world

Smart contracts operate within the blockchain ecosystem and are therefore limited to the information available within the blockchain. Smart contracts rely on oracles to interact with the outside world and receive up-to-date data such as currency exchange rates, weather conditions, or the results of sporting events.

Oracles are services or protocols that provide external data to smart contracts. However, the use of oracles introduces an element of trust into an otherwise trustless system, as a smart contract must rely on the accuracy and validity of the data provided. This creates a potential point of vulnerability and may jeopardize contract performance.

High demands on coding accuracy

The complexity and need for error-free coding of smart contracts places high demands on developers. Errors in the code can lead to serious financial losses, as was the case with DAO on Ethereum when millions of dollars were lost due to a vulnerability in the contract code. Developing secure smart contracts requires deep knowledge and expertise in cryptography and blockchain technologies.

Limitations of programming languages

Smart contract programming languages, such as Solidity for Ethereum, have their own limitations and features. Developers must fully understand these features in order to effectively utilize the full capabilities of smart contracts and avoid common mistakes.


Smart contracts represent one of the most significant advances in blockchain technology, offering a promising approach to automation and security in contract fulfillment. Their ability to conduct transactions without intermediaries not only simplifies processes, but also reduces potential costs and fulfillment time.

Quickex, as a cryptocurrency exchange platform, provides users with access to a wide range of cryptocurrencies and tokens created through smart contracts. Easily exchange Ethereum and EOS, Cardano and Tezos and many other crypto pairs on Quickex.

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