Bitcoin is a worldwide cryptocurrency and digital payment system. It’s the first decentralized digital currency. The system — created by Satoshi Nakamoto — works without a central repository.
A blockchain is a digitized, decentralized, public ledger of all cryptocurrency transactions. Blockchain has been popularized by Bitcoin and is very disruptive to all centralized corporate structures.
A cryptocurrency is a digital asset designed to work as a medium of exchange using cryptography to secure the transactions, to control the creation of additional units, and to verify the transfer of assets.
Decentralization is the process of distributing or dispersing functions, powers, people or things away from a central location or authority, such as a central bank.
Ethereum is an open-source, public, blockchain-based distributed computing platform featuring smart contract (scripting) functionality - founded by Vitalik Buterin in 2013.
Initial coin offering (ICO) is an unregulated means of crowdfunding via use of cryptocurrency, which can be a source of capital for startup companies.