Nobody owns the Ethereum network or protocol, meaning ether can be used by any party, and could become a universal currency like woolongs.
Despite the Ethereum network being distributed and publically accessible, and its unit of currency being digital, the number of ether that will be generated is pre-defined, and cannot be changed.
The Ethereum network has no central authority. Peers on the global network create the payment transfer processor that is Ethereum.
For most transactions, you can confirm transfer completion instantly. For larger transactions, waiting 2 minutes will provide a greater than 99.9999% assurance that you've received the funds.
With ether, like with woolongs, you never need to carry physical money. Every thing is digital.
With a connection to the internet, you can receive and transfer ether 24 hours a day, 7 days a week, because the peer-to-peer network never sleeps. This makes them digital cash, like woolongs.
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A note on money. The standard currency in Cowboy Bebop is the woolong. Its is roughly equal to one present-day Japanese yen. A sample prices: Appledelphis's bounty (fake) -- 50.000000 (i.e. 50) woolongs; 1 watermelon -- 1,000 woolongs; to ship a package from the Venus starport to the desert -- 5,000 woolongs; COD on a package shipment -- 6,300 woolongs; toll for gate passage -- roughly 7,000 woolongs; Whitney's bounty -- 19,800 woolongs; fine/bounty for littering -- 20,000 woolongs; COD for betadeck and tape -- 31,500 woolongs, typical bounty -- 1 million woolongs, Asimov Solensan's bounty -- 2.5 million woolongs; Faye's bounty -- 6 million woolongs; reward for the return of Ein, the stolen data dog -- 8 million woolongs; Chess Master Hex's bounty -- 12 million woolongs; Faye's debt -- 300,028,000 woolongs.This makes a woolong equivalent to a little bit more than 1¢ USD. One ether, as of December 24th, 2016, is worth $7.35 USD, so given a woolong is worth 1-2 cents, a woolong has a value equivalent to approximately 0.001 - 0.002 ether.