Practice Tests
IELTS Reading (AC) Task 1 #126

A. Blockchain is a decentralised, distributed, and often public, digital ledger that is used to record transactions across many computers so that any involved record cannot be altered retroactively without the alteration of all subsequent blocks. This technology is the foundational element behind most cryptocurrencies, such as Bitcoin, but its potential applications extend far beyond digital finance. The core innovation of blockchain is that it guarantees the fidelity and security of a record of data and generates trust without the need for a trusted third party like a bank or government.

B. A blockchain consists of a growing list of records, called blocks, which are securely linked together using cryptography. Each block contains a cryptographic hash of the previous block, a timestamp, and transaction data. This design makes blockchains inherently resistant to modification. Because the ledger is distributed across a peer-to-peer network, any attempt to alter a single block would be immediately flagged as invalid by the rest of the network, making the system highly secure and transparent.

C. While initially conceived for cryptocurrencies, blockchain technology is now being explored for a wide range of uses. In supply chain management, it can be used to track goods from origin to consumer, ensuring authenticity and preventing fraud. In healthcare, it could be used to create secure and unalterable patient records that are accessible to authorised providers. Other potential applications include voting systems, intellectual property management, and smart contracts, which are self-executing contracts with the terms of the agreement directly written into code.

D. Despite its promise, blockchain technology faces several hurdles to widespread adoption. Issues such as scalability, energy consumption (particularly for "proof-of-work" systems like Bitcoin''s), and a complex regulatory landscape remain significant challenges. Furthermore, integrating blockchain with existing legacy systems can be difficult and costly. Nevertheless, its ability to create a secure, transparent, and decentralised system for recording transactions suggests that it will continue to be a disruptive technology in the years to come.