Unravelling Oracles: The Key to Reliable Data in Smart Contracts

In the ever-evolving world of blockchain and decentralised applications (DApps), smart contracts have emerged as a game-changing innovation. These self-executing contracts with the terms of agreement written into code are autonomous, transparent, and tamper-proof. However, for all their potential, smart contracts face a significant hurdle – they cannot access real-world data outside their network. This is where oracles come into play.

What Are Oracles?

In the context of blockchain and smart contracts, oracles are third-party services that provide smart contracts with external information. They serve as bridges between blockchains and the outside world. Oracles can feed various types of data, such as price information, weather conditions, and other real-world events, into the smart contracts.

Oracles are not a data source but rather a data carrier. They transmit information from a source to a smart contract. However, the reliability of a smart contract depends on the accuracy of the data provided by the oracle.

The Role of Oracles in Smart Contracts

Smart contracts are only as good as the data they utilise. While they can manage and execute agreements without external interference, they lack the capability to gather real-world data. If a smart contract needs to execute an action based on, say, the current price of a cryptocurrency or the outcome of a football match, it needs to retrieve this information from somewhere. That’s the role of an oracle.

For example, suppose a group of individuals has a bet on a football match via a smart contract. The contract would use an oracle to determine the outcome of the game and distribute the winnings to the correct parties.

Types of Oracles

Oracles can be categorised based on several characteristics, including the type of data they provide, their source of information, and their degree of centralisation.

  1. Data Type Oracles: These oracles provide specific types of data such as price feeds, event outcomes, or weather conditions.
  2. Source Oracles: These oracles are classified based on where they get their information. Some rely on human input, while others retrieve data from software or hardware sources.
  3. Direction of Information Oracles: Some oracles send data from the outside world to the blockchain (inbound), while others send data from the blockchain to the outside world (outbound).
  4. Degree of Centralisation Oracles: Some oracles are centralised, controlled by a single entity, while others are decentralised and managed by multiple parties to reduce the risk of manipulation.

The Challenge of Trust

The use of oracles introduces an element of trust into the otherwise trustless realm of blockchain. If an oracle provides inaccurate information, a smart contract could execute in the wrong way, leading to financial loss or other issues. Therefore, the challenge lies in ensuring that oracles are reliable and that their data is accurate.

Various solutions exist to mitigate these issues, including decentralised oracles, multi-sig oracles, and trusted computing techniques. These solutions aim to ensure that data is accurate, reliable, and tamper-proof.


As the intersection between the blockchain and the real world, oracles play a pivotal role in the practical implementation of smart contracts. While challenges exist, especially around trust and reliability, ongoing developments promise to enhance the security and effectiveness of oracles. As we continue to explore the potential of blockchain technology, oracles will undoubtedly play a crucial part in this exciting journey.

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