The block reward is the payment that is offered to the node that is securing the blockchain. In the case of Bitcoin, which is has a Proof-of-Work consensus algorithm, these would be the miners. The payment is in the form of the native cryptocurrency of that blockchain. The amount is a predetermined reward per block, but often that is supplemented with the fees that are paid for the transactions that block contains. For Bitcoin the current block rewards are cut in half every four years. This is called the ‘halvening’.
A ‘51% attack’ refers to a possible attack on a blockchain by a group of ‘miners’, who hold more than 50% of the hashrate. In such a situation the ‘miners’ have the possibility to deliberately not confirm transactions or to issue transactions twice (double-spend).
DAO is an abbreviation of ‘Decentralised Autonomous Organization’. This is basically an organisation that runs automatically on itself without any human interventions. The work is automatically excecuted through Smart contracts.
An airdrop is a way to distribute coins. End users can generally get coins for free or in exchange for a small task, such as subscribing to a newsletter, sending a tweet or inviting other people via a personal affiliate link.
Blockchain is most simply defined as a decentralized, distributed ledger technology that records the provenance of a digital asset.
With digital currency, there is a risk that the holder could make a copy of the digital token and send it to a merchant or another party while retaining the original.
