Blocks are linked together by cryptography – complex mathematics and computer science. Any attempt to alter data disrupts the cryptographic links between blocks, and can quickly be identified as fraudulent by computers in the network.
While its price had fallen slightly from a 24 hour high of $68,525 on Tuesday morning to $67,983.80 as of 2.10pm, Bitcoin’s price hike still represents a year-on-year increase of more than 300% on last November’s value.

Now the country’s central bank, People’s Bank of China, has effectively banned digital coins after announcing all transactions of cryptocurrencies are illegal.
Cryptocurrency transactions are recorded on a decentralized ledger. This ledger is called a blockchain. Every time crypto is bought or sold, the transaction is added to the blockchain — a public database of the transactions, which is available to other crypto holders. Anyone can join and participate in the blockchain, but data on individual transactions — and the people involved with them — are secured using cryptography (the basis for the term cryptocurrency). For each transaction added to the blockchain, there’s a digital validation process to verify it and prevent fraud.