The Bitcoin network provides bitcoin owners with a unique sort of security – proof-of-work. Proof-of-work, or PoW, is a method for securing a network in a decentralized manner. The process, however, is incredibly energy-intensive, requiring thousands of competing processors, or miners, to perform redundant calculations. Other forms of security, say that underlying instruments listed on the Nasdaq stock exchange, rely on cheaper centralized methods.
www.coindesk.com