double-spending, or blocking transactions from being verified.</p>\n<p><strong>Blockchains with less <a href=https://www.bitdegree.org/"/crypto/learn/crypto-terms/what-is-hash-power-hashrate/">hashing power</strong></a> are more fragile to 51% attacks</strong>. With such blockchains, bad-intended miners can easily obtain the required computing power. Therefore, the more miners and resources are spent mining a blockchain, the safer the blockchain is. For instance, the <strong><a href=https://www.bitdegree.org/"/crypto/buy-bitcoin-btc/">Bitcoin network is the most secure blockchain, because it has a huge amount of hashing power acquired through mining.</p>\n<p>A few of the more well-known instances of 51% attacks happened in August 2016, when both <strong>Krypton and Shift</strong> (Ethereum-based networks) suffered from these attacks. Since then, there were quite a few similar incidents in the crypto industry.</p>","level":"easy","meta_title":"What is 51% Attack? Definition & Meaning | Crypto Wiki","meta_description":"51% Attack meaning: 51% Attack - happens when a fraudulent miner controls more than 50% of the total mining power and violates the blockchain's technology.","meta_keywords":null,"language":"en","created_at":"2022-02-10T12:54:05.000000Z","updated_at":"2022-10-26T07:42:45.000000Z","preview_url":"https://www.bitdegree.org/crypto/learn/crypto-terms/what-is-51-attack"},"prevSection":{"id":4,"original_id":null,"author_id":40,"translator_id":null,"title":"What is 24hr?","slug":"what-is-24hr","section":"1","keyword":"24hr","status":"published","definition":"The information for the previous 24 hours is represented by a 24hr time unit.","content":"<p>The information for the previous 24 hours is represented by a <strong>24hr time unit</strong>. It is mainly used when talking about the total value of crypto traded in the past 24 hours.</p>","level":"easy","meta_title":"What is 24hr? Definition & Meaning | Crypto Wiki","meta_description":"24hr meaning: 24hr - The information for the previous 24 hours is represented by a 24hr time unit.","meta_keywords":null,"language":"en","created_at":"2022-02-10T12:42:55.000000Z","updated_at":"2022-05-13T14:32:22.000000Z","preview_url":"https://www.bitdegree.org/crypto/learn/crypto-terms/what-is-24hr"},"currentChapter":"1","currentSection":"what-is-30d","chapterTitle":"1","readingLevel":"easy"},"url":"/crypto/learn/crypto-terms/what-is-30d","version":"cdd198d50cbe5c9c21c9329d7c096ffc"}" class="container-fluid d-flex crypto-book p-0">