Blockchain, a trustless and distributed consensus system, allows you to send and/or receive money from someone without turning to third-party services. By creating a distributed network of ledgers that work together to keep all transactions, contracts and accounts public, they eliminate the need for mediation to large extent via a concept named as Proof of work. Proof of work is a requirement to define an expensive computer calculation, also called mining, that needs to be performed in order to create a new group of trustless transactions (the so-called block) on a distributed ledger called blockchain. All the network’s miners compete to be the first to find a solution for the mathematical problem that concerns the candidate block, a problem that cannot be solved in other ways than through brute force, essentially requiring a huge number of attempts. When a miner finally finds the right solution, he/she announces it to the whole network at the same time, receiving a cryptocurrency prize (the reward) provided by the protocol.
Bitcoin has a cryptographic security feature to ensure that only the owner of a Bitcoin can spend it. The idea is that the owner generates two numbers—a private key that is secret and a public key that is published. The public key can be easily generated from the private key, but not vice versa. A signature can be used to verify that the owner holds the private key, without revealing the private key, using a technique known as an elliptic curve signature scheme. In this way, the receiver can verify that the owner possesses the private key and therefore has the right to spend the Bitcoin. View More