Any parties, including those involved, cannot alter a block or transaction outside of the initial reporting. It remains transparent, reliable, and accurate for the life of the chain. Further, the identities of both parties remain anonymous. Even if your closest neighbor earned millions through a recent blockchain transaction, you would have no idea unless they told you directly.
In the world of Blockchain, a "block" is the name given to a public transaction. Every time the related data changes hands, whether, through mining or a direct transaction, it is recorded in the ledger. Here is where the security comes into play: even though you can open that digital ledger and look at any one of those transactions or blocks, all you can see is the item changing hands and how much it is worth.
Blockchain Technologies use Smart contracts. The smart contract is just a phrase used to describe computer code that can facilitate the exchange of money, content, property, shares, or anything of value. A smart contract becomes like a self-operating computer program that automatically executes when specific conditions are met when running on the Blockchain.
Because smart contracts run on the Blockchain, they run exactly as programmed without any possibility of censorship, downtime, fraud, or third-party interference. Smart contracts help you exchange money, property, shares, or anything of value in a transparent, conflict-free way while avoiding the services of a middleman. So, smart contracts define the rules and penalties around an agreement in the same way that a traditional contract does and automatically enforce those obligations.