BLOCKHAİN

Blockchain technology is essentially a globally shared, transactional database. This means that everyone can read entries in the database just by participating in the network. If you want to make a change in the database, you have to create a transaction which has to be accepted by all others. The word transaction implies that the change you want to make is either not done at all or completely applied. Also, while your transaction is being applied to the database, no other transaction can alter it.
For instance, consider a table that lists the balances of all accounts in an electronic currency. If a transfer from one account to another is requested, the transactional nature of the database ensures that if the amount is subtracted from one account, it always gets added to the other account.
Moreover, every transaction is always cryptographically signed by its sender (creator). This makes it easy to guard access to specific modifications of the database. In an electronic currency scenario, for example, a simple check ensures that only the person holding the keys to an account can transfer money from it.