In October 2008, a person or group, using the pseudonym "Satoshi Nakamoto" distributed a distributed a paper called "Bitcoin: A Peer-to-Peer Electronic Cash System". In January 2009, the first bitcoin software and blockchain network was started.
The technology that supports Bitcoin, and many cryptocurrencies that have followed is called the Blockchain. The Blockchain is a series of computers that maintain the same "openledger". When a new transaction occurs, a new block gets appended to the end of the chain of transactions. All computers in the blockchain network must confirm that this is a valid transaction for approcal.
Mutiple protocol types are used for mining and verifying cryptocurrency transactions. Proof of work uses computational power to confirm a transaction. Proof of stake uses a proof of ownership as part of the verification process, Delegated proof of stake, Proof of activity - Combination of Proof of work and stake.
The cryptocurrency Ethereum added a programming layer to its blockchain implementation called a "smart contract". A smart contract specifies rules that must be performed, executed and verified for a peer to peer computerized transaction to occur.
While stocks have Initial Public Offerings(IPOs); Cryptocurrencies use Initial Coin Offerings(ICO) to gain their initial funding. Similar to buying new shares of stocks, users have the ability to be the first coin token holders prior or during the ICO period for a new cryptocurrency.
Public and Private keys created by a cryptographic system used by a cryptocurrency. The keys provides a method of authentication and encryption for blockchain transactions. The actual key codes are long strings of characters. Never share your private keys, anybody that has your private key can steal your funds. Public keys are shared and used in cryptocurrency transactions.