Is the blockchain safe? The blockchain is a continuously growing list of records called blocks which are linked and secured using cryptography. As it is a decentralized system it is maintained by multiple participants on the network who are responsible for securing the data. But, can you trust a bunch of strangers to take good care of the information? Well, as a difference with traditional institutions responsible to keep these records the blockchain was designed to be immutable.
This is how it works: every record that has been written on the blockchain is secured by a unique cryptographic key. This key is virtually unhackable. When a new record is written on the same block everything from their previous record, including its content and its key, is put into a formula to generate the key of the second record. This interaction creates dependency. When a third record is created, the content and the keys of the first two records are put into a formula to establish the third key.
This dependency essentially chains all the records together. the same process is then repeated until the block is full.
This way, every record created makes it dramatically more complex to alter history, because as an open network, anyone can verify it if the history is correct just by looking back at the previous blocks..