A block is record of a new transactions. When a block is completed, it’s added to the chain. Bitcoin owners have the private password (a complex key) to an address on the chain, which is where their ownership is recorded. Crypto-currency proponents like the distributed storage without a middle man — you don’t need a bank to verify the transfer of money or take a cut of the transaction.
The common assumption that Bitcoins are stored in a wallet is technically incorrect. Bitcoins are not stored anywhere. Bitcoin balances are kept using public and private “keys,” which are long strings of numbers and letters linked through the mathematical encryption algorithm that was used to create them. The public key (comparable to an international bank account number or IBAN) serves as the address published to the world, and to which others may send Bitcoins.

Some wallets offer a 'Receive Money' functionality. When you earn Bitcoins by accepting them as a payment method on a more regular basis it comes in handy when you use a button called 'Create Payment Request'. Here you enter the Bitcoin amount the customer has to pay and it will show the corresponding QR-code automatically. This way the customer doesn't need to enter an amount which makes the payment for them more convenient. For this method you need to calculate the Bitcoin amount from your USD or EUR price before you can enter it for the QR-code to generate.
Heath/Medical Records: Blockchain has the potential to standardize secure electronic medical record sharing across providers in a less burdensome way than previous approaches.5 It offers the ability to create a decentralized record management system that reduces the need for another organization between the patient and the records to manage access. Blockchain-enabled healthcare applications offer potential benefits such as instantly verifying the authenticity of prescriptions or automatically identifying potential adverse drug interactions.

Ponzi schemes.[28] Beware of anyone making promises that you can easily make incredibly high returns by getting in on the "ground floor" of a new phenomenon, especially if that person promises you little to no risk. You should also be on the lookout for any "investment opportunity" that does not have minimum investor qualifications, or that has complicated fee structures or strategies.[29]
Transactions are verified by network nodes through cryptography and recorded in a public distributed ledger called a blockchain. Bitcoin was invented by an unknown person or group of people using the name Satoshi Nakamoto[9] and released as open-source software in 2009.[10] Bitcoins are created as a reward for a process known as mining. They can be exchanged for other currencies,[11] products, and services. Research produced by the University of Cambridge estimates that in 2017, there were 2.9 to 5.8 million unique users using a cryptocurrency wallet, most of them using bitcoin.[12]